- Email: [email protected]
Hair Analyses
Symposium on The Laboratory in Pediatric Practice
Hair Analyses
K. Michael Hambidge, M.R.C.P.*
The laboratory use of human hair as a diagnostic tool is attracting increasing attention from physicians anrl other health professionals. However, despite some promise for the future, there are few circumstances in which hair is of established diagnostic value to the clinician. Regrettably, it is the misuse of hair analyses and their commercial exploitation which provide the primary justification for discussing this subject in the context of this volume. Before focusing on the specific subject of chemical analyses of hair, it should be noted that hair does have either established or potential value as a diagnostic sample when subjected to other procedures. For example, light microscopy can provide supportive or even definitive evidence of a number of disease states. Thus, the specific microscopic abnormalities of the hair shaft in Menkes' steely hair syndrome 16 provide a simple, rapid, and reliable method of confirming this diagnosis. To give one example of potential rather than established use, the changes in hair root morphology that occur in protein energy malnutrition 1 may be of practical value in the laboratory assessment of malnourished infants and children. It is, however, the chemical analysis of hair which was expanded so rapidly during the 1970s and which now supports a thriving commercial industry. Interest in chemical analyses began mainly in the field of forensic science. 2 As a means of identifying and distinguishing between individuals, hair analysis has not proved useful. Because of its durability, however, hair has yielded data of historical toxicologic interest, such as the high concentration of arsenic that has been found in Napoleon's hair. 20 Currently, the areas in which hair analyses are most popular are environmental pollution,12 and mineral, especially trace element, nutrition. 12 There are a number of reasons, some good but others less laudable, why the appeal of hair analyses in these areas has grown so rapidly
*Professor of Pediatrics,
University of Colorado Health Sciences Center, School of Medicine,
Denver, Colorado Supported by National Institute of ArthritiS, Metabolic and Digestive Diseases Grant No.2 RO 1 A,\U2432 and by Grant No. RR-69 fro,n the General Clinical Research Centers Program of the Division of Research Resources, National Institutes of Health. Pediatric Clinics of North America-Vol. 27, No.4, November 1980
855
856
K.
MICHAEL HAMBIDGE
in recent years. The valid reasons can best be illustrated by consideration of trace element deficiency states and the difficulties encountered in their detection through the use of more conventional samples. This has become an increasingly challenging problem as the clinical importance and scope of trace element deficiency has gained recognition. 6
Choice of Sample for Analysis of Trace Elements First, although blood plasma or serum is the time-honored, most respected and established, and, in many instances, virtually the only material available to the clinical chemist, it is technically difficult to use plasma or serum for analyses of this type, because trace elements are present in such extremely low concentrations (a few parts per billion or per trillion). Second, even when accurate data are obtained, they do not necessarily provide insight into trace element nutritional status. That fraction of the body content of a trace element which is in the circulation may not be in equilibrium with physiologically important body pools, and may at best only give an indication of recent dietary intake. 17 These and other limitations, which apply more to some trace elements than others, have stimulated research laboratories to seek other potentially useful indices of trace nutritional status, to either replace or supplement plasma concentrations. The suggested indices include measurements of physiologic functions that are dependent on a specific trace element, such as the activity of metalloenzymes, and a variety of other techniques that are not, however, generally applicable as screening procedures. Another approach, particularly with the "newer" trace elements, is to measure concentrations of trace elements in other tissues. Unfortunately, the range of sample materials that are readily available from the living human subject are strictly limited. They include the cellular constituents of blood, urine, mixed or parotid saliva, hair, and nails. Each of these samples has been the subject of reports on trace element analyses, though generally they remain in the province of the research rather than the clinical laboratory. USE OF HAIR AS A DIAGNOSTIC SAMPLE In view of the difficulties encountered in the laboratory assessment of trace element status, together with the burgeoning interest in the trace elements in relation to human health and disease, it is not surprising that the appeal of hair analyses has grown rapidly in recent years. This interest has been stimulated by a number of potentially attractive features of hair as a sample material for analysis of trace elements. Collection is relatively simple and atraumatic, though cultural taboos or individual reluctance sometimes poses a problem. Storage and transport of samples are exceptionally easy. Trace element concentrations in hair are frequently relatively high, which facilitates the analysis of the material. In addition, the analysis of scalp hair may also help to provide a long-term, albeit retrospective, evaluation of trace element status, and, if the distance from the scalp is measured, an approximate time interval can be calculated.
857
HAIR ANALYSES
While these factors increase enthusiasm for hair analyses, this sample material also has characteristics that impose substantial limitations on its potential value. The first relates to the long-term exposure of hair to the external environment, and to the concern that exogenous trace elements may be incompletely removed by standard, or even heroic, washing procedures prior to analysis. This concern has been heightened by increased exposure of scalp hair to exogenous sources of some trace elements. For example, zinc or selenium are used as additives in some commercial hair shampoos. This problem requires very careful evaluation for each individual element. In our experience in Denver, exogenous contamination with copper probably has a major influence on analytical results after standard washing procedures. 5 On the other hand, this does not appear to apply to chromium 7 or zinc 9 except under the most exceptional circumstances. There have been several studies of the effects of different hair washing procedures, but a need remains for more extensive and definitive studies for most elements. The effects of organic solvents, ionic detergents, and non-ionic detergents are comparable for several elements,8 including chromium and zinc, but not for other elements, such as iron. 8. 13 Different results may be obtained with more aggressive procedures, such as the use of chelating agents, but it is not clear whether these techniques also affect endogenous minerals. Moreover, hair color may influence the concentration of certain elements. For example, manganese concentrations are higher in black hair than in white hair. to Again, this subject requires further detailed study. Finally, interpretation of analytical data is dependent on the assumption of a normal rate of hair growth, approximately 1 cm per month. At any given time some scalp hairs are in a resting (telogen) phase. If analyses are limited to very few hair shafts, the chance selection of hairs in the resting phase may provide misleading information, at least in temporal analysis of results. Nutritional assessment is frequently desired for subjects who have evidence of generalized malnutrition. However, hair levels of trace elements can be misleadingly high if hair growth is limited by protein deprivation. If the low protein diet is accompanied by low intake of trace elements, low hair concentrations would not be expected to be found until the recovery stage of protein energy malnutrition. Severe zinc deficiency is another specific nutrient deficiency that leads to an arrest of hair growth (Table 1). In these circumstances, zinc concentrations in hair are normal or even elevated. This contrasts sharply to the marked depression of hair zinc concentrations that occur with mild dietary zinc restriction. These relationships have been demonstrated clearly in animals,18 and it is quite apparent Table 1. Laboratory Assessment o!Zinc Nutritional Status ZINC NUTRITIONAL STATUS
HAIR GROWTH
PLASMA ZINC
HAIR ZINC
Normal Mild deficiency Severe deficiency
Normal Normal Decreased
Normal Normal Decreased
Normal Decreased Normal
858
K.
MICHAEL HAMBIDGE
that they also apply to man. ls In severe zinc deficiency states, i.e., in acrodermatitis enteropathica syndromes, the hair zinc concentration is frequently not depressed; yet it may be profoundly depressed in mild chronic zinc deficiency. 9, 11 Thus, the attractive features of using hair analyses as an index of nutritional status or body burden are counterbalanced by problems that detract from its potential value with respect to specific trace elerrients. It is, indeed, unfortunately quite apparent that hair analyses alone cannot supply an answer to our growing needs. Results of hair analysis must be interpreted cautiously, with consideration of the above limitations and with awareness of the need for further research. It is, of course, true that some interesting differences in concentrations of trace elements in hair have been detected among different population groups. To give but one example, the mean hair chromium concentration of insulin-dependent diabetic children have been found to be significantly lower than that of age-matched controls.4 It should be perfectly obvious, however, that this does not indicate that all, or perhaps any, diabetic children have a clinically significant degree of chromium depletion. Nor does it imply, despite a recent suggestion to the contrary, 15 that hair chromium determinations may provide a useful screening tool for the detection of diabetes. Though this type of study can help to focus attention on populations that merit further attention in studies of human chromium nutrition and deficiency, it can do no more at this time. An individual value outside the lower limits of the range determined for an apparently normal population is not alone indicative of a deficiency state. The physiologic and nutritional significance of such a finding must also be determined. Families of children with learning disabilities are one group who have proved to be particularly vulnerable to commercial exploitation regarding hair analyses. Statistically significant differences between children with learning disabilities and control children have been reported for several elements. 19 It must be emphasized, however, that these group differences have not been shown to be clinically meaningful to any individual child. Even if an abnormally high or low hair concentration of a trace element can be shown to be associated with a clinically significant excess or deficiency, the hair analysis is not necessarily useful. For example, hair analysis can help in the detection oflead toxicity,14 but there are more widely accepted and sophisticated means of achieving this diagnosis.14 Similarly, the finding of a low hair iron concentration is not the optimal means of confirming the diagnosis of iron deficiency. Hair analyses are of greater potential value for elements from which there are no, or inadequate, alternative laboratory tools for assessing status.
HAIR ANALYSIS IN ZINC DEFICIENCY For the assessment of the trace element nutritional status of individual subjects, in the author's opinion, hair analyses have proved of some practical value only for zinc (see Table 1). At least until such time as more sensitive and precise laboratory indices of zinc deficiency states
------------------
859
HAIR ANALYSES
are developed, determination of hair zinc concentrations has a role in the detection of mild chronic zinc deficiency states. 9 However, interpretation of analytical data is fraught with difficulties, particularly in infants and young children in whom it has proved especially difficult to define a normal range. Unfortunately, this is the age group in which confirmation of a possible diagnosis of zinc deficiency is most frequently required. The uptake of zinc by hair is slow and most closely parallels that of bone. 3 This uptake may be impaired preferentially if the amount of zinc absorbed is decreased. Hence, it is possible that hair zinc levels can be markedly depressed while more vital tissues continue to receive an adequate supply and there are no symptoms of zinc deficiency. Incidentally, several studies have demonstrated a lack of any positive correlation between human hair and plasma zinc. This is to be expected and does not negate the potential value of a hair zinc determination but it does serve to emphasize that a low hair zinc value has a significance that is different from that of hypozincemia.
CONCLUSIONS The pitfalls and limitations of hair analyses have been emphasized for three reasons. First, though hair analyses have potential value in several fields including especially those of environmental pollution and trace element nutrition, further research is essential to define their role in laboratory diagnosis. Second, there has been a recent tendency to overstate the case for hair analyses. This should be balanced with a more practical review of the present state of the art. Third, more and more physicians are being asked for opinions from patients on the results of hair analyses purchased without a doctor's request from one of a growing number of commercial laboratories in many areas of the United States. Usually these reports extend over several pages and superficially appear to be very impressive. They may include ratios of one element to another and values from a large number of individual major and trace elements. The physician should not be disconcerted or bewildered by this array of data. With very few and only partial exceptions, the clinical significance and health-related importance of these figures are unknown. Unfortunately, however, it may be difficult to convince the individual patient or his parents that this detailed and quite costly record is not more meaningful, at least in the present state of our knowledge.
REFERENCES 1. Bradfield, R. B.: Hair tissue as a medium for the differential diagnosis of protein-calorie
malnutrition: A commentary. J. Pediatr., 84:294-296, 1974. 2. Coleman, R. F., Cripps, F. H., Stimson, A., et al.: The Determination of Trace Elements in Human Hair by Neutron Activation and the Application to Forensic Science. Atomic Weapons Research Establishment AWRE Report No. 0-86/66. January, 1967. 3. Deeming, S. B., and Weber, C. W.: Evaluation of hair analysiS for determination of zinc status using rats. Am. J. Clin. Nutr., 30:2047-2052,1977. 4. Hambidge, K. M.: Chromium nutrition in man. Am. J. Clin. Nutr., 27:505-514, 1974. 5. Hambidge, K. M.: Increase in hair copper concentration with increasing distance from the scalp. Am. J. Clin. Nutr., 26:1212--1215, 1973.
860
K.
MICHAEL HAMBIDGE
6. Hambidge, K. NI.: The role of zinc and other trace metals in pediatric nutrition and health. PEDIATR. CLIN. NORTH AM., 24:95-106, 1977. 7. Hambidge, K. M., Franklin, M. L., and Jacobs, M. A.: Changes in hair chromium concentrations with increasing distance from hair roots. Am. J. Clin. Nutr., 25:380,1972. 8. Hambidge, K. M., Franklin, M. L., and Jacobs, NI. A.: Hair chromium concentration: Effect of sample washing procedures and external environmental factors. Am. J. Clin. Nutr., 25:384, 1972. 9. Hambidge, K. M., Hambidge, C., Jacobs, M., et al.: Low hair zinc, anorexia, poor growth and hypogeusia in children. Pediatr. Res., 6:868-874, 1972. 10. Hambidge, K. M., Walravens, P., Kumar, V., et al.: Chromium, zinc, manganese, copper, nickel, iron and cadmium concentrations in the hair of residents of Chandigarh, India and Bangkok, Thailand. In Hemphill, D. D. (ed.): Proceedings of the Eighth Annual Conference on Trace Substances in Environmental Health. University of Missouri-Columbia, 1975, pp. 39-44. 11. Hambidge, K. M., Wravens, P. A., and Neldner, K. H.: Zinc and acrodermatitis enteropathica. In Hambidge, K. M., (ed.): Zinc and Copper in Clinical Medicine, Holliswood, N.Y., Spectrum Publications, Inc., 1977, pp. 81-98. 12. Hammer, D. I., Finklea, J. F., Hendricks, R. H., et al.: Hair trace metal levels and environmental exposure. Am. J. Epidemiol., 93:84-92, 1971. 13. Harrison, H. H., Yurachek, J. P., and Benson, C. A.: The determination of trace elements in human hair by atomic absorption spectroscopy. Clin. Chim. Acta, 23 :83-91, 1969. 14. Kopito, L., Byers, R. K., and Shwachman, H.: Lead in hair of children with chronic lead poisoning. N. Engl. J. Med., 276:949-953, 1967. 15. Maugh, T. H.: Hair: A diagnostic tool to complement blood serum and urine. Science, 202: 1271-1273, 1978. 16. Menkes, J. H., Alter, M., Steigleder, G. K., et al.: A sex-linked recessive disorder with retardation of growth, peculiar hair, and focal cerebral and cerebellar degeneration. Pediatrics, 764-779, 1962. 17. Mertz, W.: Chromium occurrence and function in biological systems. Physiol. Rev., 49:163, 1969. 18. Pallauf, J., and Kirgessner, M.: Zinkhonzentration des rattenhaares bei zinc - depletion and - repletion. Zentralblatt fur Veterinnermedizin A20, 100-108, 1973. 19. Pilil, R. 0., and Parkes, M.: Hair element content in learning disabled children. Science, 198:204-206, 1977. 20. Smith, H., Forshufvud, S., and Wassen, A.: Distribution of arsenic in Napoleon's hair. Nature, 194:725, 1962. Department of Pediatrics University of Colorado Health Sciences Center 4200 East Ninth Avenue Denver, Colorado 80262
Hair Analyses
K. Michael Hambidge, M.R.C.P.*
The laboratory use of human hair as a diagnostic tool is attracting increasing attention from physicians anrl other health professionals. However, despite some promise for the future, there are few circumstances in which hair is of established diagnostic value to the clinician. Regrettably, it is the misuse of hair analyses and their commercial exploitation which provide the primary justification for discussing this subject in the context of this volume. Before focusing on the specific subject of chemical analyses of hair, it should be noted that hair does have either established or potential value as a diagnostic sample when subjected to other procedures. For example, light microscopy can provide supportive or even definitive evidence of a number of disease states. Thus, the specific microscopic abnormalities of the hair shaft in Menkes' steely hair syndrome 16 provide a simple, rapid, and reliable method of confirming this diagnosis. To give one example of potential rather than established use, the changes in hair root morphology that occur in protein energy malnutrition 1 may be of practical value in the laboratory assessment of malnourished infants and children. It is, however, the chemical analysis of hair which was expanded so rapidly during the 1970s and which now supports a thriving commercial industry. Interest in chemical analyses began mainly in the field of forensic science. 2 As a means of identifying and distinguishing between individuals, hair analysis has not proved useful. Because of its durability, however, hair has yielded data of historical toxicologic interest, such as the high concentration of arsenic that has been found in Napoleon's hair. 20 Currently, the areas in which hair analyses are most popular are environmental pollution,12 and mineral, especially trace element, nutrition. 12 There are a number of reasons, some good but others less laudable, why the appeal of hair analyses in these areas has grown so rapidly
*Professor of Pediatrics,
University of Colorado Health Sciences Center, School of Medicine,
Denver, Colorado Supported by National Institute of ArthritiS, Metabolic and Digestive Diseases Grant No.2 RO 1 A,\U2432 and by Grant No. RR-69 fro,n the General Clinical Research Centers Program of the Division of Research Resources, National Institutes of Health. Pediatric Clinics of North America-Vol. 27, No.4, November 1980
855
856
K.
MICHAEL HAMBIDGE
in recent years. The valid reasons can best be illustrated by consideration of trace element deficiency states and the difficulties encountered in their detection through the use of more conventional samples. This has become an increasingly challenging problem as the clinical importance and scope of trace element deficiency has gained recognition. 6
Choice of Sample for Analysis of Trace Elements First, although blood plasma or serum is the time-honored, most respected and established, and, in many instances, virtually the only material available to the clinical chemist, it is technically difficult to use plasma or serum for analyses of this type, because trace elements are present in such extremely low concentrations (a few parts per billion or per trillion). Second, even when accurate data are obtained, they do not necessarily provide insight into trace element nutritional status. That fraction of the body content of a trace element which is in the circulation may not be in equilibrium with physiologically important body pools, and may at best only give an indication of recent dietary intake. 17 These and other limitations, which apply more to some trace elements than others, have stimulated research laboratories to seek other potentially useful indices of trace nutritional status, to either replace or supplement plasma concentrations. The suggested indices include measurements of physiologic functions that are dependent on a specific trace element, such as the activity of metalloenzymes, and a variety of other techniques that are not, however, generally applicable as screening procedures. Another approach, particularly with the "newer" trace elements, is to measure concentrations of trace elements in other tissues. Unfortunately, the range of sample materials that are readily available from the living human subject are strictly limited. They include the cellular constituents of blood, urine, mixed or parotid saliva, hair, and nails. Each of these samples has been the subject of reports on trace element analyses, though generally they remain in the province of the research rather than the clinical laboratory. USE OF HAIR AS A DIAGNOSTIC SAMPLE In view of the difficulties encountered in the laboratory assessment of trace element status, together with the burgeoning interest in the trace elements in relation to human health and disease, it is not surprising that the appeal of hair analyses has grown rapidly in recent years. This interest has been stimulated by a number of potentially attractive features of hair as a sample material for analysis of trace elements. Collection is relatively simple and atraumatic, though cultural taboos or individual reluctance sometimes poses a problem. Storage and transport of samples are exceptionally easy. Trace element concentrations in hair are frequently relatively high, which facilitates the analysis of the material. In addition, the analysis of scalp hair may also help to provide a long-term, albeit retrospective, evaluation of trace element status, and, if the distance from the scalp is measured, an approximate time interval can be calculated.
857
HAIR ANALYSES
While these factors increase enthusiasm for hair analyses, this sample material also has characteristics that impose substantial limitations on its potential value. The first relates to the long-term exposure of hair to the external environment, and to the concern that exogenous trace elements may be incompletely removed by standard, or even heroic, washing procedures prior to analysis. This concern has been heightened by increased exposure of scalp hair to exogenous sources of some trace elements. For example, zinc or selenium are used as additives in some commercial hair shampoos. This problem requires very careful evaluation for each individual element. In our experience in Denver, exogenous contamination with copper probably has a major influence on analytical results after standard washing procedures. 5 On the other hand, this does not appear to apply to chromium 7 or zinc 9 except under the most exceptional circumstances. There have been several studies of the effects of different hair washing procedures, but a need remains for more extensive and definitive studies for most elements. The effects of organic solvents, ionic detergents, and non-ionic detergents are comparable for several elements,8 including chromium and zinc, but not for other elements, such as iron. 8. 13 Different results may be obtained with more aggressive procedures, such as the use of chelating agents, but it is not clear whether these techniques also affect endogenous minerals. Moreover, hair color may influence the concentration of certain elements. For example, manganese concentrations are higher in black hair than in white hair. to Again, this subject requires further detailed study. Finally, interpretation of analytical data is dependent on the assumption of a normal rate of hair growth, approximately 1 cm per month. At any given time some scalp hairs are in a resting (telogen) phase. If analyses are limited to very few hair shafts, the chance selection of hairs in the resting phase may provide misleading information, at least in temporal analysis of results. Nutritional assessment is frequently desired for subjects who have evidence of generalized malnutrition. However, hair levels of trace elements can be misleadingly high if hair growth is limited by protein deprivation. If the low protein diet is accompanied by low intake of trace elements, low hair concentrations would not be expected to be found until the recovery stage of protein energy malnutrition. Severe zinc deficiency is another specific nutrient deficiency that leads to an arrest of hair growth (Table 1). In these circumstances, zinc concentrations in hair are normal or even elevated. This contrasts sharply to the marked depression of hair zinc concentrations that occur with mild dietary zinc restriction. These relationships have been demonstrated clearly in animals,18 and it is quite apparent Table 1. Laboratory Assessment o!Zinc Nutritional Status ZINC NUTRITIONAL STATUS
HAIR GROWTH
PLASMA ZINC
HAIR ZINC
Normal Mild deficiency Severe deficiency
Normal Normal Decreased
Normal Normal Decreased
Normal Decreased Normal
858
K.
MICHAEL HAMBIDGE
that they also apply to man. ls In severe zinc deficiency states, i.e., in acrodermatitis enteropathica syndromes, the hair zinc concentration is frequently not depressed; yet it may be profoundly depressed in mild chronic zinc deficiency. 9, 11 Thus, the attractive features of using hair analyses as an index of nutritional status or body burden are counterbalanced by problems that detract from its potential value with respect to specific trace elerrients. It is, indeed, unfortunately quite apparent that hair analyses alone cannot supply an answer to our growing needs. Results of hair analysis must be interpreted cautiously, with consideration of the above limitations and with awareness of the need for further research. It is, of course, true that some interesting differences in concentrations of trace elements in hair have been detected among different population groups. To give but one example, the mean hair chromium concentration of insulin-dependent diabetic children have been found to be significantly lower than that of age-matched controls.4 It should be perfectly obvious, however, that this does not indicate that all, or perhaps any, diabetic children have a clinically significant degree of chromium depletion. Nor does it imply, despite a recent suggestion to the contrary, 15 that hair chromium determinations may provide a useful screening tool for the detection of diabetes. Though this type of study can help to focus attention on populations that merit further attention in studies of human chromium nutrition and deficiency, it can do no more at this time. An individual value outside the lower limits of the range determined for an apparently normal population is not alone indicative of a deficiency state. The physiologic and nutritional significance of such a finding must also be determined. Families of children with learning disabilities are one group who have proved to be particularly vulnerable to commercial exploitation regarding hair analyses. Statistically significant differences between children with learning disabilities and control children have been reported for several elements. 19 It must be emphasized, however, that these group differences have not been shown to be clinically meaningful to any individual child. Even if an abnormally high or low hair concentration of a trace element can be shown to be associated with a clinically significant excess or deficiency, the hair analysis is not necessarily useful. For example, hair analysis can help in the detection oflead toxicity,14 but there are more widely accepted and sophisticated means of achieving this diagnosis.14 Similarly, the finding of a low hair iron concentration is not the optimal means of confirming the diagnosis of iron deficiency. Hair analyses are of greater potential value for elements from which there are no, or inadequate, alternative laboratory tools for assessing status.
HAIR ANALYSIS IN ZINC DEFICIENCY For the assessment of the trace element nutritional status of individual subjects, in the author's opinion, hair analyses have proved of some practical value only for zinc (see Table 1). At least until such time as more sensitive and precise laboratory indices of zinc deficiency states
------------------
859
HAIR ANALYSES
are developed, determination of hair zinc concentrations has a role in the detection of mild chronic zinc deficiency states. 9 However, interpretation of analytical data is fraught with difficulties, particularly in infants and young children in whom it has proved especially difficult to define a normal range. Unfortunately, this is the age group in which confirmation of a possible diagnosis of zinc deficiency is most frequently required. The uptake of zinc by hair is slow and most closely parallels that of bone. 3 This uptake may be impaired preferentially if the amount of zinc absorbed is decreased. Hence, it is possible that hair zinc levels can be markedly depressed while more vital tissues continue to receive an adequate supply and there are no symptoms of zinc deficiency. Incidentally, several studies have demonstrated a lack of any positive correlation between human hair and plasma zinc. This is to be expected and does not negate the potential value of a hair zinc determination but it does serve to emphasize that a low hair zinc value has a significance that is different from that of hypozincemia.
CONCLUSIONS The pitfalls and limitations of hair analyses have been emphasized for three reasons. First, though hair analyses have potential value in several fields including especially those of environmental pollution and trace element nutrition, further research is essential to define their role in laboratory diagnosis. Second, there has been a recent tendency to overstate the case for hair analyses. This should be balanced with a more practical review of the present state of the art. Third, more and more physicians are being asked for opinions from patients on the results of hair analyses purchased without a doctor's request from one of a growing number of commercial laboratories in many areas of the United States. Usually these reports extend over several pages and superficially appear to be very impressive. They may include ratios of one element to another and values from a large number of individual major and trace elements. The physician should not be disconcerted or bewildered by this array of data. With very few and only partial exceptions, the clinical significance and health-related importance of these figures are unknown. Unfortunately, however, it may be difficult to convince the individual patient or his parents that this detailed and quite costly record is not more meaningful, at least in the present state of our knowledge.
REFERENCES 1. Bradfield, R. B.: Hair tissue as a medium for the differential diagnosis of protein-calorie
malnutrition: A commentary. J. Pediatr., 84:294-296, 1974. 2. Coleman, R. F., Cripps, F. H., Stimson, A., et al.: The Determination of Trace Elements in Human Hair by Neutron Activation and the Application to Forensic Science. Atomic Weapons Research Establishment AWRE Report No. 0-86/66. January, 1967. 3. Deeming, S. B., and Weber, C. W.: Evaluation of hair analysiS for determination of zinc status using rats. Am. J. Clin. Nutr., 30:2047-2052,1977. 4. Hambidge, K. M.: Chromium nutrition in man. Am. J. Clin. Nutr., 27:505-514, 1974. 5. Hambidge, K. M.: Increase in hair copper concentration with increasing distance from the scalp. Am. J. Clin. Nutr., 26:1212--1215, 1973.
860
K.
MICHAEL HAMBIDGE
6. Hambidge, K. NI.: The role of zinc and other trace metals in pediatric nutrition and health. PEDIATR. CLIN. NORTH AM., 24:95-106, 1977. 7. Hambidge, K. M., Franklin, M. L., and Jacobs, M. A.: Changes in hair chromium concentrations with increasing distance from hair roots. Am. J. Clin. Nutr., 25:380,1972. 8. Hambidge, K. M., Franklin, M. L., and Jacobs, NI. A.: Hair chromium concentration: Effect of sample washing procedures and external environmental factors. Am. J. Clin. Nutr., 25:384, 1972. 9. Hambidge, K. M., Hambidge, C., Jacobs, M., et al.: Low hair zinc, anorexia, poor growth and hypogeusia in children. Pediatr. Res., 6:868-874, 1972. 10. Hambidge, K. M., Walravens, P., Kumar, V., et al.: Chromium, zinc, manganese, copper, nickel, iron and cadmium concentrations in the hair of residents of Chandigarh, India and Bangkok, Thailand. In Hemphill, D. D. (ed.): Proceedings of the Eighth Annual Conference on Trace Substances in Environmental Health. University of Missouri-Columbia, 1975, pp. 39-44. 11. Hambidge, K. M., Wravens, P. A., and Neldner, K. H.: Zinc and acrodermatitis enteropathica. In Hambidge, K. M., (ed.): Zinc and Copper in Clinical Medicine, Holliswood, N.Y., Spectrum Publications, Inc., 1977, pp. 81-98. 12. Hammer, D. I., Finklea, J. F., Hendricks, R. H., et al.: Hair trace metal levels and environmental exposure. Am. J. Epidemiol., 93:84-92, 1971. 13. Harrison, H. H., Yurachek, J. P., and Benson, C. A.: The determination of trace elements in human hair by atomic absorption spectroscopy. Clin. Chim. Acta, 23 :83-91, 1969. 14. Kopito, L., Byers, R. K., and Shwachman, H.: Lead in hair of children with chronic lead poisoning. N. Engl. J. Med., 276:949-953, 1967. 15. Maugh, T. H.: Hair: A diagnostic tool to complement blood serum and urine. Science, 202: 1271-1273, 1978. 16. Menkes, J. H., Alter, M., Steigleder, G. K., et al.: A sex-linked recessive disorder with retardation of growth, peculiar hair, and focal cerebral and cerebellar degeneration. Pediatrics, 764-779, 1962. 17. Mertz, W.: Chromium occurrence and function in biological systems. Physiol. Rev., 49:163, 1969. 18. Pallauf, J., and Kirgessner, M.: Zinkhonzentration des rattenhaares bei zinc - depletion and - repletion. Zentralblatt fur Veterinnermedizin A20, 100-108, 1973. 19. Pilil, R. 0., and Parkes, M.: Hair element content in learning disabled children. Science, 198:204-206, 1977. 20. Smith, H., Forshufvud, S., and Wassen, A.: Distribution of arsenic in Napoleon's hair. Nature, 194:725, 1962. Department of Pediatrics University of Colorado Health Sciences Center 4200 East Ninth Avenue Denver, Colorado 80262