Hungry Hungry Bones: Electrolyte Abnormalities in the Presence of Severe Malnutrition

Severe malnutrition in the presence of child maltreatment and anorexia nervosa can lead to significant effects on bones. We present a case of severe malnutrition from child maltreatment that developed into AN, osteoporosis, and persistent electrolyte abnormalities due to hungry bone syndrome (HBS). We describe a 15-year-old female with a history of medical neglect and severe malnutrition presenting to the hospital after removal from mother’s home. The patient was admitted and monitored for refeeding syndrome. She had an elevated parathyroid hormone (PTH) level (761pg/ml), vitamin D deficiency, hypocalcemia (6.3mg/dl), and hypomagnesemia (1.5mg/dl), requiring daily management for weeks. The team delayed the initial Dual-energy X-ray Absorptiometry (DXA) scan because the patient could not lie flat. Once obtained, DXA demonstrated a total-body-less-head (TBLH) Z score of -5.9 standard deviations below the age-matched mean. HBS began with secondary hyperparathyroidism after severe malnutrition; PTH increased bone resorption to maintain normal calcium levels. With refeeding, a sudden fall in PTH led to net calcium movement into bones, resulting in hypocalcemia. In patients with HBS, hypomagnesemia and hypophosphatemia may also be observed due to bone formation. Hypomagnesemia and hypocalcemia occurred in our patient and required continuous electrolyte replacement and supplementation. Although rare, providers managing refeeding syndrome among severely malnourished patients should be aware of the risk of HBS and accelerated electrolyte consumption.