Acute Water Intoxication During Military Urine Drug Screening
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MILITARY MEDICINE, 176, 4:451, 2011 Acute Water Intoxication During Military Urine Drug Screening Maj Molly A. Tilley , USAF MC ; Maj Casey L. Cotant , USAF MC ABSTRACT Random mandatory urine drug screening is a routine practice in the military. The pressure to produce a urine specimen creates a temptation to consume large volumes of water, putting those individuals at risk of acute water intoxication. This occurs when the amount of water consumed exceeds the kidney’s ability to excrete it, resulting in hyponatremia owing to excess amount of water compared to serum solutes. The acute drop in serum osmolality leads to cerebral edema, causing headaches, confusion, seizures, and death. There has been increasing awareness of the danger of overhydration among performance athletes, but dangers in other groups can be underappreciated. We present the case Downloaded from https://academic.oup.com/milmed/article/176/4/451/4345329 by guest on 23 September 2021 of a 37-year-old male Air Force offi cer who developed acute water intoxication during urine drug screening. Our case demonstrates the need for a clear Air Force policy for mandatory drug testing to minimize the risk of developing this potentially fatal condition. INTRODUCTION lying on his back in the rest room, restless, and inarticulate. Acute and chronic hyponatremia are common disorders that Intravenous normal saline was started and the patient was are associated with adverse clinical outcomes.1 Typically, acute monitored by telemetry. He had a normal sinus rhythm, with hyponatremia is encountered in the hospitalized patient with blood pressure of 140/62 and heart rate of 97. Over the next several co-morbidities or in post-surgical patients with con- few minutes, the patient was described as having “dry heaves” comitant pain and nausea. Less well-recognized is the devel- and “seizure-like activity” before curling up in the fetal posi- opment of acute hyponatremia in the setting of acute water tion. The patient was treated with lorazepam and transported intoxication. We present a case of hyponatremia in an oth- to the hospital. He remained anuric before arriving at the drug erwise healthy male precipitated by a combination of stress, testing facility. excessive fl uid consumption, and urinary retention. This case In the emergency room, a Foley catheter was placed and more highlights the need for policies to limit water intake and con- than 2 L of urine was drained. Lab results revealed hypona- stant vigilance for this serious condition in all institutions that tremia, Na 122 mEq/L (122 mmol/L), and hypokalemia, K use mandatory urine drug screening. 2.9 mEq/L (2.9 mmol/L). No urine studies were taken at that time. His exam was notable for lethargy, and the patient had CASE trouble with short-term memory. The neurologic exam was Our patient is a 37-year-old active duty Air Force male who otherwise normal. was in excellent health with a past medical history notable Ninety minutes after arrival to the hospital, the patient had only for obstructive sleep apnea treated with modafi nil and already produced 4.5 L of urine via foley catheter. By that time, continuous positive airway pressure. At approximately 7:00 his serum sodium had increased to 132 mEq/L (132 mmol/L) a.m., the patient was instructed to report for a routine military and urine osmolality was 53 mOsm/kg (53 mmol/kg). Over urine drug screen test. This test requires that the patient be the next several hours, serial lab tests ( Table I ) showed that the able to produce urine under direct visual observation, which patient continued to produce dilute urine and his serum sodium had historically been diffi cult for the patient. In an unsuccess- level was getting normal . Neither IV fl uid nor dietary restric- ful attempt to produce urine, the patient drank sixteen 30-oz tion were prescribed. Once the patient’s sodium had normal- containers (over 14 L) of water between the 9:00 a.m. and ized to 139 mEq/L (139 mmol/L), the patient’s urine output 12:00 p.m. decreased and essentially matched his intake. His neurologi- Approximately 3 hours after commencing his water intake, cal status completely normalized, the patient was discharged the staff noticed that the patient was complaining of abdomi- the next afternoon, and his drug test returned negative. No nal pain and acting confused. At 2:20 p.m., the patient’s odd efforts were made to slow his rate of correction because his behavior and abdominal pain prompted the transfer of the hyponatremia was thought to be acute and the risk of osmotic patient to the Family Practice Clinic. Eighty minutes later, demyelination was thus low. a code blue was called by a passerby who found the patient DISCUSSION Hyponatremia, defi ned as a serum sodium concentration of Wilford Hall Medical Center, 2200 Bergquist Drive, Suite 1, Lackland less than 136 mEq/L (136 mmol/L), is commonly encoun- AFB, TX 78236. 1 The views expressed in this article are those of the authors and do not nec- tered in clinical practice. Hypotonic hyponatremia, refl ecting essarily refl ect the offi cial policy or position of the United States Air Force, an excess of water relative to solute, is most commonly caused Department of Defense, or the U.S. Government. by an impaired ability of the kidney to excrete free water, as is MILITARY MEDICINE, Vol. 176, April 2011 451 Case Report TABLE I. Review of Laboratory Results she recovered uneventfully after the administration of 1.4 L of IV normal saline and supplemental potassium chloride. Serum Na Serum K Serum Osm Urine Osm Both cases were felt to be secondary to excessive water mEq/L mEq/L mOsm/kg mOsm/kg (mmol/L) (mmol/L) (mmol/L) (mmol/L) intake in a short amount of time, but SIADH may have played Day 1, 4:30 p.m. 122 2.9 n/r n/r a role as well. Situational stress, nausea, and vomiting may 23–25 Day 1, 6:00 p.m. 122 3.0 n/r n/r induce a transient SIADH. Additionally, a recent review Day 1, 9:00 p.m. 132 4.1 265 53 of 6 elderly patients with hyponatremia and urinary retention Day 2, 12:40 a.m. 136 3.4 281 180 revealed that 5 out of the 6 patients had lab criteria consistent Day 2, 4:00 a.m. 139 4.0 289 27 with SIADH. In all 6 cases, the hyponatremia resolved after Day 7, 9:00 a.m. 138 4.6 288 496 urinary catheterization and fl uid restriction, suggesting that n/r, not recorded. bladder distension and pain might have led to SIADH. 26 Our Downloaded from https://academic.oup.com/milmed/article/176/4/451/4345329 by guest on 23 September 2021 patient had many risk factors for SIADH, including functional seen in the syndrome of inappropriate anti-diuretic hormone bladder failure, pain, and anxiety. (SIADH). Less frequently seen is an excessive water intake, Given the potential for acute water intoxication, various overwhelming the kidney’s ability to excrete the free water recommendations have been made regarding limits of water load, leading to subsequent hyponatremia.1–3 Often, these con- consumption in persons undergoing urinary drug screening. ditions overlap, such that hyponatremia develops in the setting Klonoff and Jurow recommend no more than 1 L of water be of excessive water intake in addition to a concomitant defect consumed per hour. 8 In 2002, Gardner and Gutman, in agree- in renal-free water excretion. ment with contemporarily published Army guidelines, recom- The deleterious effects of acute hyponatremia relate to mended that fl uid intake should not exceed 40 ounces during abrupt changes in the extracellular osmolality and the subse- the drug-testing session. 22 quent translocation of water down its concentration gradient Army Regulation 600-85 ( http://acsap.army.mil ) re-iterated into the cell, leading to cerebral edema, headache, confusion, that “the Soldier will be allowed to drink 8 ounces of water seizure, brain-stem herniation, and death. 1,4,5 The rapid devel- every 30 minutes but not to exceed a total volume of 40 ounces opment of hyponatremia is catastrophic because the brain in 3 hours.” 27 The Department of Transportation and the has not had time to equilibrate and decrease the intracellu- Department of Justice also have similar standards. 22 However, lar osmolality by the extrusion of intracellular solutes such as the U.S. Air Force Instruction (AFI) 44-120 does not place potassium and organic osmolytes. 1,6,7 limits on fl uid consumption. For those with paruresis, the AFI Our patient presented with presumed acute symptomatic provides a thorough section regarding “shy bladder or situ- hyponatremia in the setting of a urine drug screen and parure- ational anxiety,” but fails to specify a suffi cient time or an sis. Paruresis, a phobia that makes it diffi cult or impossible for adequate amount of fl uid that should be consumed before a a patient to urinate in public, is present in approximately 30% patient is evaluated for this disorder. 28 Even more challenging, of men and 25% of women. 8,9 The lack of micturation leads to the airman is expected to have a medical waiver for paruresis more water intake in an effort to initiate voiding, potentially before the date of his/her random drug testing. It is clear that making the patient at risk for the development of hypona- the consequences of not providing a sample under such vague tremia if >1 L/hour of water is consumed.