In rare cases, pancytopenia results from hormonal deficiencies that arise in the setting of panhypopituitarism. Here we describe the unusual case of a 60-year-old man who presented with progressive fatigue and polyuria, and whose laboratory workup revealed a deficiency of the five hormones associated with the action of the anterior pituitary (thyroid hormone, testosterone, cortisol, prolactin, and insulin-like growth factor-1). Imaging of the pituitary demonstrated a cystic mass consistent with a pituitary adenoma replacing much of the normal pituitary tissue. His symptoms and hematologic abnormalities rapidly resolved with prednisone and levothyroxine supplementati on. While the m ajority of r eported cases of panhypopituitarism with bone marrow suppression are the result of peripartum sepsis or hemorrhage leading to pituitary gland necrosis (Sheehan's syndrome), it is also important to consider the diagnosis of hypopituitarism in patients with hypothyroidism, low cortisol levels, and pancytopenia. The causal relationship between pancytopenia and panhypopituitarism is not well understood, though it does reinforce the important influence of these endocrine hormones on the health of the bone marrow.
CASE PRESENTATIONA 60-year-old man was admitted to Massachusetts General Hospital with chest pain thought to be the result of his longstanding gastroesophageal reflux disease. He had a history of glaucoma, atypical nevi, and diverticulosis. He reported progressively worsening fatigue and weakness, a 10 lb weight loss, polyuria, and increased thirst. Laboratory testing on presentation was notable for hyponatremia (116 mmol/L) and pancytopenia. Out of concern for an underlying malignancy, the patient underwent contrast-enhanced computed tomography scans of the chest, abdomen, and pelvis, which were unremarkable. Given his progressive fatigue and hyponatremia, a morning serum cortisol level was checked and found to be very depressed (1.0 μg/dL; normal range 5-25 μg/dL). This prompted a more extensive endocrine evaluation (Table 1) that resulted in documentation of low levels of thyroid hormone, cortisol, testosterone, prolactin, and insulin-like growth factor-1 (IGF-1). A diagnosis of panhypopituitarism was made based on the reduced levels of all five hormones associated with the action of the anterior pituitary. A cosyntropin stimulation test demonstrated an inappropriately low increase in serum cortisol levels (1.2 to 7.4 μg/dL), suggesting reduced adrenal responsiveness due to prolonged adrenocorticotropic hormone (ACTH) deficiency. Though euvolemic, the patient displayed hyponatremia, with elevated urine osmolality, suggesting a component of elevated antidiuretic hormone (ADH) thought to be compensatory in the setting of glucocorticoid deficiency.In evaluation of the pituitary gland, MRI demonstrated a 6 mm cystic lesion in the posterior aspect of the pituitary (Fig. 1a). The radiologic appearance was most consistent with a cystic pituitary adenoma compressing and replacing the normal tissue of the pituitary gland. ...