Hungry bones syndrome is a disorder characterized by significant and persistent hypocalcemia, even though serum parathormone levels may be normal or even augmented. This disorder occurs following an increase of the bone formation to bone resorption ratio, a state which leads to the abundant amount of calcium than that required by the organism.
Hungry bones syndrome most commonly occurs following parathyroidectomy and is attributed to the increased influx of calcium into the bone, after circulating serum parathormone has been subjected to an abrupt decrease  . The disorder leads to profound hypocalcemia and hypophosphatemia, findings which give rise to various symptoms.
The considerable hypocalcemia causes cardiovascular and neurologic or neuromuscular symptoms. The symptoms associated with hungry bones syndrome include syncopic events, angina pectoris, and congestive heart failure . Bradycardia, tachycardia, an S3 cardiac tone and signs such as dyspnea, fatigue and edemas may be observed.
As far as neurological symptoms are concerned, hungry bones syndrome may lead to irritability, profound fatigue, and exhaustion, as well as depression, psychosis, hallucinations and personality alterations. The patient may exhibit the epileptic activity of various types, such as petit or grand mal seizures and focal epilepsy, while intellectual capacity and perception may also appear abnormally decreased. Neuromuscular involvement may be observed, as the patient may develop dysphagia or laryngospasm due to contractions of the smooth muscles or wheezing sounds, that can be heard during auscultation. The patient may also report paresthetic phenomena in the extremities, as well as cramps in the feet and back, that may be further exacerbated to the point that tetany appears . Intestinal and biliary colic can also occur as a result of hypocalcemia, as can hemiballism, parkinsonism, and choreoathetosis .
The physical examination for hypocalcemia includes the Chvostek and Trousseau signs . The positive Chvostek sign is indicative of hypocalcemia and encompasses a tap on the skin above the facial nerve about 2 cm anterior to the external auditory meatus, which elicits an ipsilateral contraction of the facial muscles. However, the Chvostek sign can exist in conditions other than hypocalcemia and is, therefore, non-specific for the condition. The Trousseau sign involves a carpal spasm, induced when a blood pressure cuff is inflated to 20 mmHg for approximately 5 minutes.
Acute hypocalcemia constitutes a medical emergency and should be promptly evaluated and corrected.
As a first step, true hypocalcemia should be distinguished from factitious hypocalcemia . Serum albumin needs to be measured, in order to detect whether the patient is suffering from true hypocalcemia (decreased ionized calcium) or factitious hypocalcemia, otherwise referred to as pseudohypocalcemia, where the total calcium is decreased, but ionized calcium remains unaffected.
Parathyroid hormone (parathormone or PTH) levels also need to be evaluated; vitamin D measurement is also mandatory, should there be any suspicion towards its deficiency. Parathormone insufficiency may coexist with normal or mildly decreased serum alkaline phosphatase (ALP). Liver function tests need to be performed in order to assess the overall hepatic functionality, alongside coagulation factors, blood urea nitrogen and creatinine levels.
Electrocardiography can also be employed in order to detect a potentially prolonged QT segment . A plain radiograph can also help to illustrate malignancies or benign tumors of the skeletal system, that may lead to hypocalcemia.