Laryngospasm in hypoparathyroidism

Diagnosis and management of hypocalcemia

The aim of this clinical narrative review is to summarize and critically appraise the literature on the differential diagnosis of hypocalcemia and to provide its correct management. Calcium is essential for muscle contraction and neurotransmitter release, but clinical manifestations of hypocalcaemia (serum calcium level <8 mg/dl; 2.12 mmol/L) may involve almost any organ and system and may range from asymptomatic to life-threating conditions. Disorders causing hypocalcemia can be divided into parathyroid hormone (PTH) and non-PTH mediated. The most frequent cause of hypocalcemia is postsurgical hypoparathyroidism, while a more comprehensive search for other causes is needed for appropriate treatment in the non PTH-mediated forms. Intravenous calcium infusion is essential to raise calcium levels and resolve or minimize symptoms in the setting of acute hypocalcemia. Oral calcium and/or vitamin D supplementation is the most frequently used as treatment of chronic hypocalcemia. In hypoparathyroidism, providing the missing hormone with the use of the recombinant human (rh) PTH(1-84) has been recently approved both by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). This new therapy has the advantage of being effective for correcting serum calcium levels and significantly reducing the daily requirements of calcium and active vitamin D supplements. However, due to the high cost, a strict selection of candidates to this therapy is necessary. More challenging is the long-term hypocalcemia treatment, due to its associated complications. The development of long-acting recombinant human PTH will probably modify the management of chronic hypoparathyroidism in the future.

Clinical presentation and management of hypoparathyroidism

The clinical manifestations of hypoparathyroidism are variable and can involve almost any organ system. The main clinical features of the hypoparathyroidism are typically signs or symptoms due to neuromuscular irritability owing to low serum calcium level. In addition to hypocalcemia, hyperphosphatemia can contribute to long-term complications, including extra-skeletal calcifications. Bone turnover markers are generally decreased, and bone mass density is usually normal-increased compared to age- and gender-matched controls. It is still unclear whether or not these bone features could have an impact on the risk of fracture. Impaired renal function is a common complication described in patients treated for hypoparathyroidism. Other complications include premature cataracts, seizures, basal ganglia calcifications, and cardiac arrhythmias. Lastly, some clinical studies have also reported a reduced quality of life of patients with hypoparathyroidism. Increased awareness of the clinical manifestations of this disease is important to improve its clinical management.

Hypoparathyroidism

Hypoparathyroidism is a disease characterized by inadequately low circulating concentrations of parathyroid hormone (PTH) resulting in low calcium levels and increased phosphate levels in the blood. Symptoms of the disease result from increased neuromuscular irritability caused by hypocalcaemia and include tingling, muscle cramps and seizures. The most common cause of the disease is inadvertent removal of, or injury to, the parathyroid glands during neck surgery, followed by genetic, idiopathic and autoimmune aetiologies. Conventional treatment includes activated vitamin D and/or calcium supplements, but this treatment does not fully replace the functions of PTH and can lead to short-term problems (such as hypocalcaemia, hypercalcaemia and increased urinary calcium excretion) and long-term complications (which include nephrocalcinosis, kidney stones and brain calcifications). PTH replacement has emerged as a new treatment option. Clinical trials using human PTH(1-34) and PTH(1-84) showed that this treatment was safe and effective in studies lasting up to 6 years. Recombinant human PTH(1-84) has been approved in the United States and Europe for the management of hypoparathyroidism; however, its effect on long-term complications is still being evaluated. Clinical practice guidelines, which describe the consensus of experts in the field, have been published and recognize the need for more research to optimize care. In this Primer, we summarize current knowledge of the prevalence, pathophysiology, clinical presentation and management of hypoparathyroidism.

Adult primary hypoparathyroidism: A rare presentation

The common causes of stridor in adults are abscesses or swelling of upper airway, tumors, paralysis or malfunction of vocal cords. Laryngospasm due to hypocalcemia is a rare cause of stridor in adults, although occasionally reported in the neonates. We report an elderly lady having stridor and laryngospasm, secondary to acquired hypoparathyroidism and secondary hypocalcemia, without risk factors for hypoparathyroidism such as recent neck surgery or irradiation. We did an extensive review of literature to find only a few cases of acquired primary hypoparathyroidism in adults with the only complaint being stridor. This case underlines the fact that a common symptom like stridor rarely occurs due to uncommon causes. This case is being reported for its rarity and amenability to complete cure in event of correct diagnosis.

Idiopathic Hypoparathyroidism and Hyperthyroidism

A case of idiopathic hypoparathyroidism is reported. The patient had presented symptoms for 16 years and various treatments and diagnoses had been tried before the correct conclusion was reached. Adequate treatment resulted in normalization of most of the symptoms. The patient also had hyperthyroidism, an exceptional combination. A possible relationship between the two diseases is discussed.

Brief upper airway (laryngeal) dysfunction

We describe in six men, recurrent episodes recurring over months or years, of sudden, brief complete obstruction to respiration followed by dyspnoea with loud inspiratory stridor lasting two to five minutes. Attacks occurred during wakefulness and/or sleep. In one patient an episode was witnessed endoscopically: the initial obstruction was seen to be caused by complete laryngeal closure. The false vocal cords then opened, but the vocal cords remained adducted and caused inspiratory stridor. The similarity of the attacks described by the other patients suggests that they were all caused by laryngeal closure. Furthermore, they could simulate the episodes by voluntarily adducting their vocal cords. The symptoms were usually preceded by a sensation of throat irritation and in four cases symptoms of upper respiratory infection were present. Associated features present in some of the patients included post-nasal discharge, snoring, sleep apnoea and gastro-oesophageal reflux. None was hypocalcaemic. Although stimulation of laryngeal receptors is known to produce reflex laryngeal closure, cough is the usual response during wakefulness. Treatment aimed at reducing upper airway irritation and voluntary inhibition of coughing appeared successful in reducing the incidence and severity of the episodes. Recognition of the condition is important as it may be confused with other causes of acute dyspnoea and it appears to respond to specific management.

Laryngeal tetany: an unusual presentation of chronic renal failure

The presenting features and subsequent management of two adult patients with chronic renal failure complicated by laryngospasm are described. Possible mechanisms to explain this uncommon phenomenon are discussed but its rarity remains unexplained.