INTRAVENOUS GLUCOSE-TOLERANCE, INSULIN, AND FREE-FATTY-ACID LEVELS IN BURNED PATIENTS

1113

INTRAVENOUS GLUCOSE-TOLERANCE, INSULIN, AND FREE-FATTY-ACID LEVELS IN BURNED PATIENTS S. P. ALLISON B.A., M.B. Cantab., M.R.C.P. MEDICAL RESEARCH COUNCIL CLINICAL RESEARCH FELLOW, DEPARTMENT OF MEDICINE, UNIVERSITY OF BIRMINGHAM

PAMELA HINTON M.B. REGISTRAR,

BURNS

UNIT,

M. CONSULTANT

Glasg.,

M.R.C.P.

Patients

J. CHAMBERLAIN BIRMINGHAM

Intravenous glucose-tolerance tests performed during the shock phase of burn injury, and repeated 1-4 weeks later, show that in the shock phase there is glucose intolerance, a high level of free fatty acids, and failure of the plasma-immunoreactiveinsulin level to rise in response to intravenous glucose. These changes have been shown to be related to the severity of the burn ; they may be due to the high level of adrenaline secretion found in such patients. In the later phase there were higher than normal blood-levels of fasting insulin and of insulin response to glucose, suggesting insulin resistance. It is suggested that burned patients should be put on a high-carbohydrate regimen, which, in view of these results, should be in the form either of glucose and insulin or of fructose.

Summary

Introduction FAILURE of insulin response to intravenous glucose, with glucose intolerance and high levels of free fatty acid (F.F.A.) in the blood, have been demonstrated during surgical operations and in the acute phase of myocardial infarction (Allison, Prowse, and Chamberlain 1967). It was postulated that these changes were a non-specific effect of stress, related to adrenaline secretion, in view of the demonstration by Porte et al. (1966) that adrenaline can suppress insulin response to glucose infusion in normal subjects. It seemed of interest to extend this study to other forms of acute stress-e.g., burns-in which high levels of adrenaline secretion and sympathetic activity are known to occur (Birke et al. 1957, Goodall et al. 1957, Harrison 1967). The high levels of adrenaline and noradrenaline excretion which persist for many days after a burn were shown to correlate in degree with the severity of the burn, and also with the secretion of adrenocortical TABLE I-BLOOD-SUGAR, FREE-FATTY-ACID

*

(1)

acute

(F.F.A.),

blood-sugar levels (Sevitt 1957) and plasma-F.F.A. concentrations (Birke et al. 1965) follow burns as they do many other forms of stress. The high levels of these metabolites have been previously ascribed to increased glycogenolysis, gluconeogenesis, and lipolysis brought about by adrenal medullary and cortical hormones. The present study was designed to investigate the part played by insulin. Patients and Methods

BIRMINGHAM ACCIDENT HOSPITAL

M.B. Birm., M.R.C.P. PHYSICIAN, DUDLEY ROAD HOSPITAL,

hormones, which was also raised (Birke et al, 1957). High

6 patients were studied. Age, sex, height, weight, and area of burn assessed by the method of Bull and Fisher (1954), are shown in table i. Patients 1-4 had severe burns and required treatment for shock. Patient 4 is included in this group, for, although the area of his burn was not large, it involved the underlying fat and muscle to a considerable depth. He also had laryngeal obstruction from inhalation of hot air, requiring tracheostomy. To eliminate the effects of fasting, the initial study was performed within the first 12 hours of the burn in all except 1 patient (patient 3), who was studied 48 hours after his burn. All patients had been previously healthy and on a normal diet. They were being treated with plasma infusion at the time of the acute study, but no additional carbohydrate had been given. The plasma was made up with distilled water. A further study was performed 1-4 weeks later, at a time when the patient was recovering. In the case of patient 1 improvement was temporary, and she died of infection 3 weeks after admission.

Glucose-tolerance Tests One or more baseline blood-samples were taken, and then a standard 25 g. intravenous glucose-tolerance test was performed in each study. The glucose was injected in 50% solution over 3 minutes into an arm vein. Blood-samples were withdrawn, through an anaesthetised area of skin, from an antecubital vein at 2, 5, 10, 20, 30, 40, 50, and 60 minutes after the end of the glucose injection. Glucose tolerance was assessed as the rate of disappearance of sugar from the blood, or k value, measured as the slope of the sugar curve plotted logarithmically (Samols and Marks 1965). Blood-sugar was measured by the ’

Auto-Analyzer ’technique (’ Neocuprin ’).

Plasma-insulin Venous blood

was taken into sodium-heparin tubes and placed immediately in a refrigerator at 4°C. All samples were centrifuged and separated within 2 hours. Plasma-immunoreactive-insulin (I.R.I.) was estimated by a modification of the method of Hales and Randle (1963).

Plasma-F.F.A. Venous blood was treated in the same way as for insulin measurement. Estimation was carried out within 24 hours by

AND IMMUNOREACTIVE-INSULIN LEVELS IN

study; (2) follow-up study

1-4 weeks later.

6 BURNED PATIENTS

1114 the Dole double-extraction technique (Dole and Meinertz 1960), followed by colorimetric measurement (Duncombe

TABLE II-BLOOD-SUGAR LEVELS

AFTER

(mg.

3 HOURS’ FAST,

IN

PER

6

100

MI.)

AT

9 A.M. DAILY,

BURNED PATIENTS

1963). Results

The results figs. 1-3.

are

shown in table

i

and illustrated in

Glucose Tolerance

Baseline levels of blood-sugar were above normal in ttnf: 1-4- and in all cases fell between the acute and

follow-up study. High blood-sugar levels persisted for several days in the patients with more severe burns, falling gradually but rising again during episodes of deterioration. The levels of blood-sugar at 9 A.M. daily, after 3 hours’ fast, are shown in table 11. In patient 1 there was a fall in blood-sugar level at 2 weeks, at a time when she was beginning to improve, but a rise terminally as septicaemic shock supervened. The other patients show a gradual but fluctuating decrease in blood-sugar levels. The k value was below normal (Samols and Marks 1965) in the acute study in all except patient 5, and was considerably higher in the later study. Or.1.

The baseline levels of plaSma-I.R.I were higher than normal (6-25 units per ml in this laboratory) in both the acute and the later study (see table i). In the acute study there was virtually no rise in plasma-i.R.I. levels in response to intravenous glucose in patients 1, 2, and 4. There was some response in patient 3, but this may reflect the fact that the study was carried out 48 hours after the burn. In all cases the plasma-i.R.I. levels in response, to glucose were higher at the follow-up study and in patients 2, 3, 5, and 6 were very high, suggesting insulin resistance. body 1, age 44, with burns of 60% later. weeks 1-4 studv; (2) follow-up study

Fig. 1-Patient (1)

acute

2-Patient no. 2,

Fig. (1) and (2)

as

in

area.

no.

fig.

1.

age

body 19, with burns of 40%

F.F.A.

The concentrations of

area.

Fig. 3-Patient

(1)

and

(2)

as

no.

in fig.

5, 1.

plasma-F.p.A.

age

42, with

were

burns of 21 00

higher in the

body

area.

1115

than the follow-up study in 5 out of 6 patients. The level of F.F.A. did not reflect the severity of the burn in these patients. The percentage fall in F.F.A. level 20 minutes after injection of glucose was lower in the acute than the follow-up study in all except patient 3. acute

Discussion to is difficult It interpret the baseline levels of I.R.I. in these burned seen patients in terms of normal values units (6-25 perlml.). In the patients with severe burns the levels of plasma-I.R.I. may not be considered high in relation to the high blood-sugar levels observed. In those with mild burns, however, the high plasma-i.R.I. levels in the presence of relatively normal blood-sugar levels could be interpreted as demonstrating insulin resistance in these patients. The high baseline levels of plasma-i.R.I. seen in the later studies in all patients suggest continuing and even increasing insulin resistance at this stage. The results of the measurement of I.R.I. levels in response to injected glucose in these studies suggests that two changes in insulin metabolism follow burns. Firstly, in the shock phase there is a failure of insulin response to injected glucose and later the development of insulin resistance. In the patients with severe burns, the first of these changes predominates, giving way to the second as the acute phase of the illness passes. In those with mild burns, the second change predominates from the beginning. It seems likely that both these changes are nonspecific effects of stress, for the same results have been seen as a consequence of surgery, myocardial infarction, trauma, and subarachnoid hxmorrhage (Allison, Prowse, and Chamberlain 1967, and unpublished). It seems likely that suppression of insulin response is mediated through heightened adrenaline secretion and sympathetic activity in view of the observations of Porte et al. (1966). However, it was not thought justifiable to subject these patients to powerful a-adrenergic blockade in order to prove this. It would be of interest to examine blockers for therashocked patients having
peutic

reasons.

development of insulin resistance after trauma is striking. Welborn et al. (1966) demonstrated this change after abdominal operations, and showed that it was unlikely to be due to increased secretion of adrenocortical hormones or growth hormone. Bailey (1960) has shown insulin resistance in patients with pseudo-diabetes of burns, in whom there is increasing hyperglycxmia beginning 1-2 weeks after a burn (Lancet 1965). It seems possible that some change in the plasma or at the cell membrane in such patients causes insulin resistance. Vallance-Owen and Ashton (1963) have shown an increased level of synalbumin in 19 out of 28 patients convalescing from myocardial infarction. Perhaps this change is an acquired and reversible consequence of the illness rather than a sign of an innate tendency to diabetes -it may be that such a change may occur in patients with burns or indeed any other form of physical stress. Baseline blood-sugar levels were in general highest in the patients with severe burns. The effect of age is impossible to assess in such a small group. Although the patients in this study were fed high-calorie diets this may have been insufficient for their much increased requirements, and it is possible that relative starvation played a part in causing insulin resistance. The significance of k values in this context is difficult to evaluate. k values do not necessarily equate with glucose utilisation, and it is conceivable that the high blood-sugar levels attained in the acute studies The

diffuse passively into the cells despite insulin response. Samols and Marks (1965) and Buchanan and McKiddie (1967) showed a correlation between k values and insulin response, and in our patients the lowest k values were in those with the poorest insulin response. We reported the percentage fall in F.F.A. at 20 minutes after injection of glucose since this seemed to be the time of maximum fall in the follow-up studies and in the normal subjects we have studied. High F.F.A. levels are probably a consequence of increased adrenergic activity, but failure of these levels to fall substantially after glucose injection may be another reflection of poor insulin response. Birke et al. (1965) showed that increased levels of F.F.A. are related to the extent of the burn injury. Our results do not necessarily conflict with this view, for the number of patients in our study was small, and the observations were made very early in the illness and not on successive days as in the Swedish series. In most cases the metabolic consequences of trauma may be relatively unimportant to the survival of the patient. It may matter little, for instance, that a healthy man, undergoing inguinal herniorrhaphy has a rise in blood-sugar level or an increased output of adrenocortical or medullary hormones. However, in more serious situations such as severe burns, these changes may be such as to prejudice the survival of the patient. Burn injury causes a dramatic hypercatabolic state in which the basal metabolic-rate can be increased to + 100% (Roe 1965), and the daily caloric requirement may be between 3000 and 6000 C. per day (Sevitt 1957). Glycogen reserves are quickly exhausted and gluconeogenesis from protein breakdown is accelerated. The patient is dependent on mobilising fat reserves, and this intense lipolysis causes a high level of plasma-F.F.A. leading to massive deposits of fat in the liver (Fergelson et al. 1961). Gross fatty infiltration of the liver in burned patients is well recognised (Sevitt 1957). It would seem logical therefore to institute intensive feeding at the time of enabled

glucose

the absence of

to

an

admission, giving ample carbohydrate to spare protein and reduce lipolysis. It is clear from these studies that in the acute phase glucose alone would be useless, for much of it would pass out into the urine with consequent osmotic diuresis and upset of water and electrolyte balance. However, glucose together with insulin might be useful. Many severely burned patients drift into a " sick-cell syndrome ": the serum-sodium level falls and the potassium level rises, while there is sodium retention and potassium loss by the kidney. It is possible that these changes partly represent a failure of the " cation pump ", so that sodium passes into the cells in exchange for potassium. We (unpublished) have been able to reverse this situation in some patients by giving 50% glucose and insulin intravenously. A rise in serum-sodium concentration ensues with a sodium diuresis and a fall in serumpotassium. As an alternative to glucose and insulin, fructose, which is not insulin-dependent for its metabolism, might be superior. At present we are comparing glucose and fructose tolerance in burned patients, and our initial findings suggest that fructose is removed rapidly from the blood even in the acute phase. X’e thank Miss Ann Unitt and Mrs. Christine Haynes for invaluable technical help; Prof. T. P. Whitehead and the department of biochemistry for measuring blood-sugar levels; Dr. R. F. Fletcher and Prof. John Hardwicke for encouragement and helpful criticism; and Mr. D. M. Jackson and Mr. J. S. Cason of the burns unit, and Mr. P. S. London of the trauma unit of the Birmingham Accident

1116 their support of this study. We also thank the Medical Research Council for supporting one of us (S. P. A.) and financing purchase of equipment. Requests for reprints should be sent to S. P. A., University Department of Medicine, Queen Elizabeth Hospital, Birmingham 15.

Hospital for

REFERENCES

Allison, S. P., Prowse, K., Chamberlain, M. J. (1967) Lancet, i, 478. Bailey, B. N. (1960) Br. med. J. ii, 1783. Birke, G., Carlson, L. A., Liljedahl, S. O. (1965) Research in Burns. 2nd International Congress; p. 78. Edinburgh. Duner, H., Liljedahl, S. O., Pernow, B., Plantin, L. O., Troell, L. (1957) Acta chir. scand. 114, 87. Buchanan, K. D., McKiddie, M. T. (1967) J. Endocr. 39, 13. Bull, J. P., Fisher, A. J. (1954) Ann. Surg. 139, 269. Dole, V. P., Meinertz, H. (1960) J. biol. Chem. 235, 2595. Duncombe, W. G. (1963) Biochem. J. 88, 7. Fergelson, E. B., Pfaff, W. W., Karmen, A., Steinberg, D. (1961) J. clin. Invest. 40, 2171. Goodall, M., Stone, C., Haynes, B. W. (1957) Ann. Surg. 145, 479. Hales, C. N., Randle, P. J. (1963) Biochem. J. 88, 137. Harrison, T. (1967) J. Trauma, 7, 137. Lancet (1965) ii, 225. Porte, D. Jr., Graber, A. L., Kwzwza, T., Williams, R. H. (1966) J. clin. Invest. 45, 228. Roe, C. F. (1965) Research in Burns. 2nd International Congress; p. 178. Edinburgh. Samols, E., Marks, V. (1965) Lancet, i, 462. Sevitt, S. (1957) Burns. Pathology and Therapeutic Applications. London. Vallance-Owen, J., Ashton, W. L. (1963) Lancet, i, 1226. Ross, H., Johnston, I. D. A., Welborn, T. A., Wright, A. D. (1966) ibid. ii, 563. —

CLINICAL AND BIOCHEMICAL STUDIES OF A PATIENT WITH A CORTICOSTERONESECRETING ADRENOCORTICAL TUMOUR R. FRASER

V. H. T. JAMES

Ph.D. Lond.

D.Sc. Lond.

RESEARCH ASSISTANT

PROFESSOR OF CHEMICAL ENDOCRINOLOGY

J. LANDON M.D. Lond. SENIOR LECTURER STEROID RESEARCH ST.

MARY’S

UNIT, DEPARTMENT OF CHEMICAL PATHOLOGY, SCHOOL, LONDON W.2

HOSPITAL MEDICAL

W. S. PEART

ANNETTE RAWSON Lond., M.R.C.P.

M.D. Lond., F.R.C.P.

M.B.

PROFESSOR OF MEDICINE MEDICAL

UNIT,

ST.

C. A. GILES CHIEF

RESEARCH ASSISTANT

MARY’S HOSPITAL,

LONDON W.2

A. M. MCKAY M.B., B.Sc. Glasg.

TECHNICIAN,

DEPARTMENT OF

LECTURER,

STEROID BIOCHEMISTRY

DEPARTMENT OF PATHOLOGY

steroids such as aldosterone, cortisol (hydrocortisone), or the adrenal androgens. The patient described here is therefore of interest since she manifested the signs and symptoms which resulted from the presence of an adrenocortical carcinoma which was secreting predominantly corticosterone.

Case-report 55-year-old housewife, was well until February, 1966, when she began to feel lethargic and to experience headaches, several times a week. Over the next few months she became progressively more tired and weak and bilateral pitting oedema of her ankles developed. Because of these symptoms she consulted her medical practitioner in July, 1966, who found that she was hypertensive. He diagnosed hypertensive cardiac failure and prescribed digoxin and a diuretic (’ Lasix’, frusemide). Within 4 days her condition had The

patient,

a

deteriorated significantly. The oedema extended to involve the calves and in addition to her previous symptoms, she experienced parsesthesiae of her face and hands, polyuria, and polydipsia. Episodes of acute weakness also occurred so that, at times, she was unable to stand or walk. When seen by a medical specialist (Dr. A. Swanepool) her blood-pressure was 210/110 mm. Hg, there was clinical and radiological evidence of left ventricular hypertrophy, striking bilateral pitting oedema, s-T and T wave depression of her electrocardiogram, and biochemical evidence of hypokalaemic alkalosis (table i). A diagnosis of hyperaldosteronism due to an adrenal tumour was considered likely. Oral efferverscent potassium chloride (6 g. daily) was substituted for her previous therapy and resulted in a notable symptomatic improvement. On admission to St. Mary’s Hospital in August, 1966, the only additional clinical finding was of a mass just palpable in the left loin. There was no papilloedema and she showed none of the clinical manifestations of Cushing’s disease.

Preliminary Investigations Haemoglobin 89%, white-blood-cell count 6000 per c.mm. with 100 eosinophils per c.mm. ; erythrocyte-sedimentation rate 24 mm. in lst hour (Westergren); plasma-sodium, 148 meq. per litre; plasma-potassium 2-0 meq. per litre; blood-urea 25 mg. per 100

ml.; serum-calcium 8-4

mg. per 100

Summary

patient with hypertension, œdema, polyuria, and weakness is described. At A

laparotomy an adrenal carcinoma was found, and removal of the tumour produced a temporary improvement in her clinical condition. Plasma steroid investigations revealed normal levels of aldosterone and cortisol but corticosterone levels were 25-50 times normal. It is postulated that the clinical syndrome was produced by the excessive secretion of corticosterone and this seems to be the first report of such a condition. Introduction

CORTICOSTERONE is normally a minor secretory product of the human adrenal cortex, and even when adrenal hyperfunction occurs because of adrenal hyperplasia or tumour, only relatively small amounts of this hormone are produced. For this reason the clinical manifestations associated with these conditions are predominantly those caused by the abnormally high plasma levels of other

serum-

abdominal calcification or abnormal soft-tissue shadow was revealed by plain X-ray. Nephrograms obtained using retrono

UNIVERSITY OF GLASGOW

ml.;

inorganic-phosphorus 2-6 mg. per 100 ml.; liver-function tests (bilirubin, alkaline phosphatase, cholesterol, serum glutamicoxaloacetic and glutamic-pyruvic transaminases, bromsulphthalein excretion, total proteins, and protein electrophoresis) were all normal. Her total body exchangeable sodium was high and potassium low, the low potassium being associated with persistent urinary and faecal potassium losses (table I). Creatinine clearance 76 ml. per minute; oral glucose tolerance normal. There was no radiological evidence of osteoporosis and

TABLE I-ELECTROLYTE DATA