Hypoparathyroidism: etiology, clinical manifestation, current diagnostics and treatment

Abstract

Parathyroid hormone (PTH) is the main regulator of calcium and phosphorus metabolism. PTH deficiency or tissue resistance to its effects results in hypoparathyroidism characterized by low serum calcium and elevated serum phosphate levels. The most common is post-operative hypoparathyroidism caused by an inadvertent damage or removal of the parathyroid glands, deterioration of blood supply to the neck region, most often during thyroid surgery. The second common form of the disease is the autoimmune one related with immune destruction of parathyroid cells. Less frequent causes of hypoparathyroidism include a variety of genetic syndromes, mitochondrial genome defects, and hypomagnesemia. The main signs and symptoms of hypoparathyroidism are related to hypocalcaemia and hyperphosphatemia land result in increased neuromuscular irritability and general autonomic reactivity, with finger and toe tingling, muscle cramps, tonic seizures, laryngo- and bronchospasm, and neurosis. These symptoms are closely associated with serum calcium levels; their severity depends on the degree of hypocalcaemia. Laboratory parameters confirming the diagnosis of hypoparathyroidism are hypocalcaemia, hyperphosphatemia, and reduced serum PTH. Treatment of hypoparathyroidism involves management of hypocalcaemic crisis and maintenance therapy. Acute hypocalcaemia, a  potentially life-threatening condition, is treated as an emergency with intravenous calcium combined with oral calcium and active vitamin D. Standard chronic treatment for hypoparathyroidism is based on oral calcium and active metabolites of vitamin  D / vitamin  D analogs and is aimed at the balance between optimal low-normal serum calcium concentrations and normocalciuria. Worsening hypercalciuria is often underestimated by specialists, although it can cause severe renal problems, such as nephrocalcinosis and neprolithiasis. Hypoparathyroidism is one of the few endocrine deficiencies for which replacement treatment with recombinant PTH is not widely used. Replacement therapy with recombinant human PTH is a  promising area, especially in severe clinical cases, refractory to conventional treatment.