SESSION TYPE: Critical Care Student/Resident Case Report Posters I
PRESENTED ON: Tuesday, October 23, 2012 at 01:30 PM - 02:30 PM
INTRODUCTION: Central diabetes insipidus is a condition characterized by excretion of large volumes of dilute urine secondary to either a deficiency in the production or release of arginine vasopressin. Glucocorticoids are necessary for the kidneys to excrete salt free water. Symptoms of central diabetes insipidus may be masked by concomitant ACTH deficiency. Polyuria may appear when corticosteroid replacement is instituted. We present a case of a woman who developed shock and was given dexamethasone for secondary adrenal insufficiency subsequently unmasking diabetes insipidus.
CASE PRESENTATION: A 40-year-old Caucasian female with a remote history of pituitary surgery, presented with a 2-month history of recurrent vomiting, diarrhea and generalized weakness. Physical examination demonstrated drowsiness, tachycardia and hypotension. Initial labs revealed hyponatremia of 130 mmol/dl, hypokalemia 3.1mmol/dl, urine specific gravity of 1.030 and normal renal function. She was started on normal saline boluses but subsequently required vasopressors for refractory shock. Her work up included a serum cortisol which was found to be very low at 0.9 mcg/dl (normal cortisol level 5-25 mcg/dl). Cosyntropin stimulation test was positive for secondary adrenal insufficiency, and dexamethasone was initiated. The patient‘s symptoms resolved, however she subsequently developed polyuria. Further workup now revealed a low urine osmolality of 209 mOsmol/kg, plasma osmolality of 307 mOsmol/kg and hypernatremia of 149 mmol/dl. She was started on desmopressin for a new diagnosis of central diabetes insipidus. The patient improved and was discharged home on dexamethasone and desmopressin.
DISCUSSION: Diabetes insipidus is defined as the excessive urinary loss of solute-free water demonstrated by polyuria (> 2 ml/kg/hr). Cortisol plays a role in maintaining blood pressure and volume. When its levels are decreased, blood pressure decreases, which stimulates the release of vasopressin. Vasopressin increases water reabsorption in the kidney. If a person has diabetes insipidus concomitant with adrenal insufficiency and is treated with cortisol, the previously masked diabetes insipidus can rapidly manifest. As seen our case, polyuria ensued when dexamethasone was started for shock due to adrenal insufficiency. Desmopressin is the drug of choice for the treatment of central diabetes insipidus.
CONCLUSIONS: Although rare, polyuria after initiating steroids is concerning for the unmasking of diabetes insipidus. Evaluation of urine and serum osmolality, as well a water deprivation test is the best ways to make the diagnosis, while desmopressin should be used for treatment.
1) Baylis, PH, Cheetham, P, Diabetes Insipidus. Arch Dis Child 1998;79:84-89
DISCLOSURE: The following authors have nothing to disclose: Hetalben Patel, Phillip Augustine, Richard Fremont
No Product/Research Disclosure InformationMeharry Medical College, Nashville, TN