Hypoparathyroidism is characterized by reduced serum calcium and increased serum phosphate concentrations, in conjunction with reduced parathyroid hormone (PTH) secretion. This condition can be caused by damage to, or removal of, parathyroid tissue but has also been observed in various syndromic disorders.
Hypoparathyroidism can also occur in isolation, such as in the context of familial isolated hypoparathyroidism (FIH) or autosomal dominant hypocalcemia (ADH). In these instances, the condition is typically caused by inactivating variants in the PTH or GCM2 genes, or activating variants in the GNA11 or CASR gene, as observed in ADH patients.
The condition known as autosomal dominant hypocalcemia (ADH) is also characterized by consistently decreased serum calcium levels, but with normal or only slightly decreased PTH concentration. Although hypocalcemia can sometimes be asymptomatic, the clinical presentation can vary significantly and may include severe recurrent seizures. An adjustment of the calcium level in these cases can lead to increased urinary calcium excretion, potentially resulting in renal failure. Therefore, any therapeutic measures should only be undertaken with close monitoring.
Baumgartner-Parzer et al. 2018, J. Klin. Endokrinol. Stoffw. 11:51 / Cinque et al. 2017, JCEM, 102:3961 / Hendy et al. 2017, Endotext [Internet] MDText.com, Inc., South Dartmouth (MA) / Clarke et al. 2016, J Clin Endocrinol Metab 101:2284 / Hannan et al. 2016, J Mol Endocrinol 57:R127 / Tenhola et al. 2016, Eur J Endocrinol 175:211 / Kinoshita et al. 2014, J Clin Endocrinol Metab 99:E363 / Raue et al. 2011, Clin Endocrinol (Oxf) 75:760