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Rapid Correction of Severe Hyponatremia After Computed Tomography With Intravenous Contrast
LETTERS TO THE EDITOR
close to the right-arm ECG lead and distant from the bipolar left leg-left arm lead (III). Depending on the location of the track on the disk, the scanning rate of CD players ranges between 200 and 530 rpm, with slower scanning rates toward the outer portion of the disk and faster rates near the center. This ensures a constant rate of transferring data, 176 kb/s, conforming to a standard established in the 1970s.1 On the basis of the rate of “flutter” waves of 333/min on our subject’s ECG, we hypothesize that the music track being scanned was near the mid portion of the disk. Summary. Although other rhythmic artifactual conditions, such as parkinsonian tremor, have been known to mimic atrial flutter,2-4 to our knowledge, based on a MEDLINE search, this observation has not been reported previously in association with the use of a personal portable CD player. Physicians should be aware of this potential cause of ECG artifacts. Stephen M. Austin, MD Stephen D. Flach, MD, PhD Carol M. Gaines, MD Covance Clinical Research Unit Madison, Wis 1. Städje J. The case of the exploding CD-ROM record. Available at: www.paintbug.com/cdexplode/. Accessed January 11, 2007. 2. Marquez MF, Colin L, Guevara M, Iturralde P, Hermosillo AG. Common electrocardiographic artifacts mimicking arrythmias in ambulatory monitoring. Am Heart J. 2002;144:187-197. 3. Rubenfire M, Rosenzweig S. Electrocardiographic artifacts simulating atrial flutter. JAMA. 1972;220:1130. 4. Koh TW. A case of atypical atrial flutter induced during coronary angiography? J Cardiovasc Electrophysiol. 2005;16:798-800.
Rapid Correction of Severe Hyponatremia After Computed Tomography With Intravenous Contrast To the Editor: Overly rapid correction of hyponatremia is a major concern in severely hyponatremic patients because of the potential development of osmotic demyelination. Numerous factors can contribute to overly rapid correction of hyponatremia (Table 1).1 We report a case in which a patient developed osmotic diuresis after contrast dye injection that rapidly self-corrected the severe hyponatremia. Report of a Case. A 59-year-old woman with diabetes mellitus and hypertension presented with a 1-week history of slow mentation, fatigue, nausea, vomiting, abdominal pain, and subjective left hemiparesthesia. A dietary history revealed that she routinely ate only fruits and cereals and drank only water. Her medications included hydrochlorothiazide, fosinopril, atenolol, metformin, and aspirin. Physical examination revealed dry oral mucosa, slow mentation, and generalized sluggish deep tendon reflexes. On initial evaluation, the serum sodium concentration was 115 mEq/L, and urinary studies revealed an osmolality of 526 mosm/kg, a sodium level of 130 mEq/L, and a chloride level of less than 10 mEq/L. The patient was given two 500-mL boluses of normal saline during the first 12 hours of hospitalization. In the interim, she underwent 384
Mayo Clin Proc.
•
TABLE 1. Potential Causes of Overly Rapid Correction of Hyponatremia Unawareness of the recommended rate of correction for hyponatremia Miscalculations Unrecognized sources of sodium Exogenous Sodium administration at another site before transfer to the current unit Addition of excess salt to patient’s diet by patient’s family or facility staff members Endogenous Potassium supplementation with resultant extracellular sodium shift Excess free water loss Water deprivation in primary polydipsia Withdrawal of thiazide diuretics during treatment of hyponatremia Glucocorticoid replacement in a cortisol-deficient patient Recovery from acute respiratory failure Excessive gastrointestinal, pulmonary, or skin hypotonic fluid loss Severe hyponatremia with subsequent cerebral edema and pituitary infarction Nonelectrolyte osmotic diuresis: urea, glucose, mannitol, contrast dye, total parenteral nutrition Intracellular free water shift Seizures Rhabdomyolysis Correction of hyperglycemia Potassium supplementation Adapted from Proceedings of UCLA HealthCare,1 with permission.
computed tomography of the head and abdomen with intravenous contrast (iohexol). Despite correction of the hypovolemia, the patient had no improvement in her symptoms or serum sodium concentration during the first 24 hours. However, approximately 24 to 26 hours after presentation, she developed progressive polyuria (up to 150-175 mL/h). During the polyuric phase, the urine osmolality ranged from 217 to 393 mosm/kg. During the subsequent few hours, the patient’s mentation noticeably improved in association with a spontaneous rapid increase in serum sodium concentration (8 mEq/L over 6 hours). In fact, hypotonic saline had to be administered to halt the rapid self-correction of the hyponatremia. Given the patient’s history of poor dietary nutrition, use of hydrochlorothiazide, and current pain and vomiting, we suspected that the hyponatremia resulted from ongoing water intake concurrent with the patient’s inability to excrete free water maximally because of a reduced dietary solute load and syndrome of inappropriate secretion of antidiuretic hormone– induced enhanced free water reabsorption.2,3 Despite saline infusion, the patient’s serum sodium concentration remained at 115 mEq/L 12 to 18 hours after presentation, presumably a reflection of the sustained syndrome of inappropriate secretion of antidiuretic hormone caused by her nausea and pain. However, by 24 hours after presentation, the patient had a rapid increase in urinary output as well as serum sodium concentration despite the discontinuation of all intravenous fluids at least 6 hours previously. At that point, the patient possibly had adequate volume reexpansion, reduced proximal tubular reabsorption of salt and water, and resultant increased distal delivery for excretion. In addition, the control of nausea
March 2007;82(3):383-386
•
www.mayoclinicproceedings.com
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
LETTERS TO THE EDITOR
and pain and the volume reexpansion may have inhibited antidiuretic hormone secretion sufficiently to result in the aquaretic phase. However, subsequent urinary electrolyte studies revealed high osmolality (217-393 mosm/kg) relative to serum osmolality (240-264 mosm/kg), which suggested that she had osmotic diuresis, not aquaresis. Further analysis of her urine by ultraviolet spectrophotometry revealed that the predominant source of the urine osmolality during the polyuric phase was the contrast dye iohexol. The findings in this case are important because computed tomography with intravenous contrast is performed routinely for the evaluation of nonspecific complaints in severely hyponatremic patients. Phuong-Chi T. Pham, MD Olive View-UCLA Medical Center Sylmar, Calif Phuong-Truc T. Pham, PhD Pennsylvania State University Wilkes-Barre, Pa Phuong-Mai T. Pham, MD Central Maine Medical Center Lewiston, Me Son V. Pham, MD University of California at Davis Sacramento VA Medical Center Sacramento, Calif Jeffrey M. Miller, MD Olive View-UCLA Medical Center Sylmar Calif Phuong-Thu T. Pham, MD David Geffen School of Medicine at UCLA Los Angeles, Calif 1. Pham P-CT, Pham P-MT, Miller J, et al. Treatment of chronic hyponatremia. Proc UCLA Healthcare. Fall 2002;6:32-36. 2. Fichman MP, Vorherr H, Kleeman CR, Telfer N. Diuretic-induced hyponatremia. Ann Intern Med. 1971;75:853-863. 3. Thaler SM, Teitelbaum I, Berl T. “Beer potomania” in non-beer drinkers: effect of low dietary solute intake. Am J Kidney Dis. 1998;31:1028-1031.
Association Between Oral Contraceptive Use and Premenopausal Breast Cancer: Mediated by Hormonal Confounders? To the Editor: Kahlenborn et al1 performed a meta-analysis of 34 case-control studies of the relationship between oral contraceptive (OC) use and premenopausal breast cancer. They found that OC use was associated with a risk of breast cancer that was slightly, but significantly, increased (odds ratio, 1.19; 95% confidence interval, 1.09-1.29). Confounding factors are a major issue in the interpretation of all case-control studies. For example, I previously noted that confounding is to be expected in case-control studies of the associations between conditions that are truly caused by Mayo Clin Proc.
•
high or low levels of steroid hormones and some forms of risky behavior (treated as risk factors).2 In the case of premenopausal breast cancer, the disease is thought to be partially caused by high levels of estrogenic (and perhaps androgenic) hormones. Moreover, the behavioral trait of sensation seeking is associated with high levels of both estrogenic and androgenic hormones.3 In contrast to agematched controls, a higher proportion of young female sensation seekers would be expected to choose to engage in voluntary “risky” behavior, eg, smoking, OC use, and abortion. Thus, the association of OCs with breast cancer may simply be a reflection of the independent association of both these factors with high levels of estrogens and/or androgens. The point could be tested by assaying the hormones of control subjects and of young women at the time they first choose to use OCs. I hypothesize that, at the time of OC initiation, users have higher hormone levels than controls. Of course, even if confounding is present, that would not imply that it is the sole cause of the association between OC use and breast cancer. Moreover, the argument would be altered if OC use directly affects women’s steroid hormone concentrations. William H. James, PhD University College London London, England Dr Kahlenborn was given the opportunity to respond but declined because he believed Dr James’ comments were in agreement with most of the points in his article. 1. Kahlenborn C, Modugno F, Potter DM, Severs WB. Oral contraceptive use as a risk factor for premenopausal breast cancer: a meta-analysis. Mayo Clin Proc. 2006;81:1290-1302. 2. James WH. Hypothesis: gonadal hormones act as confounders in epidemiological studies of the associations between some behavioural risk factors and some pathological conditions. J Theor Biol. 2001;209:97-102 3. Zuckerman M. Behavioral Expressions and Biosocial Bases of Sensation Seeking. Cambridge, England: Cambridge University Press; 1994.
Estimating Glomerular Filtration Rate From Serum Creatinine in the General Population To the Editor: In their innovative article on the limitations of estimating glomerular filtration rate (GFR) from serum creatinine levels in the general population, Rule et al1 suggest that the currently esteemed Modification of Diet in Renal Diseases (MDRD) equation is limited by the most fundamental of flaws—it was derived from an inappropriate population, namely, a cohort of subjects already diagnosed with chronic kidney disease (CKD). Thus, it is conceivable that the MDRD equation overdiagnoses CKD. In an attempt to improve on the MDRD formula, Rule et al propose 2 new equations. The first is derived from subjects free of kidney disease and incontrovertibly underdiagnoses CKD. For instance, the 60-year-old woman described in their article would require a serum creatinine level of at least 2.2
March 2007;82(3):383-386
•
www.mayoclinicproceedings.com
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
385
close to the right-arm ECG lead and distant from the bipolar left leg-left arm lead (III). Depending on the location of the track on the disk, the scanning rate of CD players ranges between 200 and 530 rpm, with slower scanning rates toward the outer portion of the disk and faster rates near the center. This ensures a constant rate of transferring data, 176 kb/s, conforming to a standard established in the 1970s.1 On the basis of the rate of “flutter” waves of 333/min on our subject’s ECG, we hypothesize that the music track being scanned was near the mid portion of the disk. Summary. Although other rhythmic artifactual conditions, such as parkinsonian tremor, have been known to mimic atrial flutter,2-4 to our knowledge, based on a MEDLINE search, this observation has not been reported previously in association with the use of a personal portable CD player. Physicians should be aware of this potential cause of ECG artifacts. Stephen M. Austin, MD Stephen D. Flach, MD, PhD Carol M. Gaines, MD Covance Clinical Research Unit Madison, Wis 1. Städje J. The case of the exploding CD-ROM record. Available at: www.paintbug.com/cdexplode/. Accessed January 11, 2007. 2. Marquez MF, Colin L, Guevara M, Iturralde P, Hermosillo AG. Common electrocardiographic artifacts mimicking arrythmias in ambulatory monitoring. Am Heart J. 2002;144:187-197. 3. Rubenfire M, Rosenzweig S. Electrocardiographic artifacts simulating atrial flutter. JAMA. 1972;220:1130. 4. Koh TW. A case of atypical atrial flutter induced during coronary angiography? J Cardiovasc Electrophysiol. 2005;16:798-800.
Rapid Correction of Severe Hyponatremia After Computed Tomography With Intravenous Contrast To the Editor: Overly rapid correction of hyponatremia is a major concern in severely hyponatremic patients because of the potential development of osmotic demyelination. Numerous factors can contribute to overly rapid correction of hyponatremia (Table 1).1 We report a case in which a patient developed osmotic diuresis after contrast dye injection that rapidly self-corrected the severe hyponatremia. Report of a Case. A 59-year-old woman with diabetes mellitus and hypertension presented with a 1-week history of slow mentation, fatigue, nausea, vomiting, abdominal pain, and subjective left hemiparesthesia. A dietary history revealed that she routinely ate only fruits and cereals and drank only water. Her medications included hydrochlorothiazide, fosinopril, atenolol, metformin, and aspirin. Physical examination revealed dry oral mucosa, slow mentation, and generalized sluggish deep tendon reflexes. On initial evaluation, the serum sodium concentration was 115 mEq/L, and urinary studies revealed an osmolality of 526 mosm/kg, a sodium level of 130 mEq/L, and a chloride level of less than 10 mEq/L. The patient was given two 500-mL boluses of normal saline during the first 12 hours of hospitalization. In the interim, she underwent 384
Mayo Clin Proc.
•
TABLE 1. Potential Causes of Overly Rapid Correction of Hyponatremia Unawareness of the recommended rate of correction for hyponatremia Miscalculations Unrecognized sources of sodium Exogenous Sodium administration at another site before transfer to the current unit Addition of excess salt to patient’s diet by patient’s family or facility staff members Endogenous Potassium supplementation with resultant extracellular sodium shift Excess free water loss Water deprivation in primary polydipsia Withdrawal of thiazide diuretics during treatment of hyponatremia Glucocorticoid replacement in a cortisol-deficient patient Recovery from acute respiratory failure Excessive gastrointestinal, pulmonary, or skin hypotonic fluid loss Severe hyponatremia with subsequent cerebral edema and pituitary infarction Nonelectrolyte osmotic diuresis: urea, glucose, mannitol, contrast dye, total parenteral nutrition Intracellular free water shift Seizures Rhabdomyolysis Correction of hyperglycemia Potassium supplementation Adapted from Proceedings of UCLA HealthCare,1 with permission.
computed tomography of the head and abdomen with intravenous contrast (iohexol). Despite correction of the hypovolemia, the patient had no improvement in her symptoms or serum sodium concentration during the first 24 hours. However, approximately 24 to 26 hours after presentation, she developed progressive polyuria (up to 150-175 mL/h). During the polyuric phase, the urine osmolality ranged from 217 to 393 mosm/kg. During the subsequent few hours, the patient’s mentation noticeably improved in association with a spontaneous rapid increase in serum sodium concentration (8 mEq/L over 6 hours). In fact, hypotonic saline had to be administered to halt the rapid self-correction of the hyponatremia. Given the patient’s history of poor dietary nutrition, use of hydrochlorothiazide, and current pain and vomiting, we suspected that the hyponatremia resulted from ongoing water intake concurrent with the patient’s inability to excrete free water maximally because of a reduced dietary solute load and syndrome of inappropriate secretion of antidiuretic hormone– induced enhanced free water reabsorption.2,3 Despite saline infusion, the patient’s serum sodium concentration remained at 115 mEq/L 12 to 18 hours after presentation, presumably a reflection of the sustained syndrome of inappropriate secretion of antidiuretic hormone caused by her nausea and pain. However, by 24 hours after presentation, the patient had a rapid increase in urinary output as well as serum sodium concentration despite the discontinuation of all intravenous fluids at least 6 hours previously. At that point, the patient possibly had adequate volume reexpansion, reduced proximal tubular reabsorption of salt and water, and resultant increased distal delivery for excretion. In addition, the control of nausea
March 2007;82(3):383-386
•
www.mayoclinicproceedings.com
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
LETTERS TO THE EDITOR
and pain and the volume reexpansion may have inhibited antidiuretic hormone secretion sufficiently to result in the aquaretic phase. However, subsequent urinary electrolyte studies revealed high osmolality (217-393 mosm/kg) relative to serum osmolality (240-264 mosm/kg), which suggested that she had osmotic diuresis, not aquaresis. Further analysis of her urine by ultraviolet spectrophotometry revealed that the predominant source of the urine osmolality during the polyuric phase was the contrast dye iohexol. The findings in this case are important because computed tomography with intravenous contrast is performed routinely for the evaluation of nonspecific complaints in severely hyponatremic patients. Phuong-Chi T. Pham, MD Olive View-UCLA Medical Center Sylmar, Calif Phuong-Truc T. Pham, PhD Pennsylvania State University Wilkes-Barre, Pa Phuong-Mai T. Pham, MD Central Maine Medical Center Lewiston, Me Son V. Pham, MD University of California at Davis Sacramento VA Medical Center Sacramento, Calif Jeffrey M. Miller, MD Olive View-UCLA Medical Center Sylmar Calif Phuong-Thu T. Pham, MD David Geffen School of Medicine at UCLA Los Angeles, Calif 1. Pham P-CT, Pham P-MT, Miller J, et al. Treatment of chronic hyponatremia. Proc UCLA Healthcare. Fall 2002;6:32-36. 2. Fichman MP, Vorherr H, Kleeman CR, Telfer N. Diuretic-induced hyponatremia. Ann Intern Med. 1971;75:853-863. 3. Thaler SM, Teitelbaum I, Berl T. “Beer potomania” in non-beer drinkers: effect of low dietary solute intake. Am J Kidney Dis. 1998;31:1028-1031.
Association Between Oral Contraceptive Use and Premenopausal Breast Cancer: Mediated by Hormonal Confounders? To the Editor: Kahlenborn et al1 performed a meta-analysis of 34 case-control studies of the relationship between oral contraceptive (OC) use and premenopausal breast cancer. They found that OC use was associated with a risk of breast cancer that was slightly, but significantly, increased (odds ratio, 1.19; 95% confidence interval, 1.09-1.29). Confounding factors are a major issue in the interpretation of all case-control studies. For example, I previously noted that confounding is to be expected in case-control studies of the associations between conditions that are truly caused by Mayo Clin Proc.
•
high or low levels of steroid hormones and some forms of risky behavior (treated as risk factors).2 In the case of premenopausal breast cancer, the disease is thought to be partially caused by high levels of estrogenic (and perhaps androgenic) hormones. Moreover, the behavioral trait of sensation seeking is associated with high levels of both estrogenic and androgenic hormones.3 In contrast to agematched controls, a higher proportion of young female sensation seekers would be expected to choose to engage in voluntary “risky” behavior, eg, smoking, OC use, and abortion. Thus, the association of OCs with breast cancer may simply be a reflection of the independent association of both these factors with high levels of estrogens and/or androgens. The point could be tested by assaying the hormones of control subjects and of young women at the time they first choose to use OCs. I hypothesize that, at the time of OC initiation, users have higher hormone levels than controls. Of course, even if confounding is present, that would not imply that it is the sole cause of the association between OC use and breast cancer. Moreover, the argument would be altered if OC use directly affects women’s steroid hormone concentrations. William H. James, PhD University College London London, England Dr Kahlenborn was given the opportunity to respond but declined because he believed Dr James’ comments were in agreement with most of the points in his article. 1. Kahlenborn C, Modugno F, Potter DM, Severs WB. Oral contraceptive use as a risk factor for premenopausal breast cancer: a meta-analysis. Mayo Clin Proc. 2006;81:1290-1302. 2. James WH. Hypothesis: gonadal hormones act as confounders in epidemiological studies of the associations between some behavioural risk factors and some pathological conditions. J Theor Biol. 2001;209:97-102 3. Zuckerman M. Behavioral Expressions and Biosocial Bases of Sensation Seeking. Cambridge, England: Cambridge University Press; 1994.
Estimating Glomerular Filtration Rate From Serum Creatinine in the General Population To the Editor: In their innovative article on the limitations of estimating glomerular filtration rate (GFR) from serum creatinine levels in the general population, Rule et al1 suggest that the currently esteemed Modification of Diet in Renal Diseases (MDRD) equation is limited by the most fundamental of flaws—it was derived from an inappropriate population, namely, a cohort of subjects already diagnosed with chronic kidney disease (CKD). Thus, it is conceivable that the MDRD equation overdiagnoses CKD. In an attempt to improve on the MDRD formula, Rule et al propose 2 new equations. The first is derived from subjects free of kidney disease and incontrovertibly underdiagnoses CKD. For instance, the 60-year-old woman described in their article would require a serum creatinine level of at least 2.2
March 2007;82(3):383-386
•
www.mayoclinicproceedings.com
For personal use. Mass reproduce only with permission from Mayo Clinic Proceedings.
385