HYPOGLYCEMIA AND HYPONATREMIA: A HIGHER CAUSE. E.J. Dzielak 1 , N.C. Chiappetta 2 ; 1 Dunmore, PA; 2 Moses Taylor Hospital, Scranton, PA (Tracking ID #77122) LEARNING OBJECTIVES: DDX of hypoglycemia W/U of and DDX of primary, secondary and tertiary causes of adrenal insufficiency. CASE INFORMATION: A 74 year-old man with past medical history of hypothyroidism, prostate carcinoma, iron deficiency anemia, paroxysmal atrial fibrillation, and hyponatremia, presented nausea and vomitting. Physical exam was normal. Abnormal laboratory data included a sodium of 125, glucose of 40, and mild normocytic anemia. His hypoglycemia did not correct with exogenous glucose administration. An A.M. cortisol level returned as 1.3. ACTH level was then drawn and returned as 20 pg/ml. Further evaluation to distinguish between secondary and tertiary adrenal insufficiency was preformed with a corticotropin stimulation test. The results of this test confirmed the diagnosis of secondary adrenal insufficiency. IMPLICATIONS/DISCUSSION: Secondary adrenal insufficiency is a deficiency of ACTH from the anterior pituitary gland resulting in a decreased production of cortisol . In the adrenal gland, ACTH stimulates the zona fasiculata, while having minimal affect on the zona glomerulosa. Therefore, manifestations of aldosterone deficiency (hyperkalemia and hypotension) are not present, as this case demonstrated. To confirm adrenal insufficiency, an AM cortisol level of <1.3 is needed. If the cortisol level is greater than 1.3, the diagnosis of adrenal insufficiency could be confirmed by a cosyntropin stimulation test. To distinguish between primary and secondary adrenal insufficiency, an ACTH level should be drawn which should be >100 pg/ml in primary adrenal insufficiency. The Metyrapone and Insulin Induced Hypoglycemia tests confirm secondary adrenal insufficiency. To distinguish between tertiary and secondary adrenal insufficiency, the corticotropin stimulation test is indicated. An absent response from baseline with ACTH and cortisol confirms secondary adrenal insufficiency, while an prolonged and exaggerated ACTH repsonse is consistent with tertiary adrenal insufficiency.