An interesting case of coexistence of autosomal dominant hypocalcemia 1 with Bartter syndrome and chronic myelogenous leukemia

Autosomal dominant hypocalcemia type 1 (ADH1) is a rare form of hypoparathyroidism caused by heterozygous, inherited, or de novo activating mutations in the calcium-sensing receptor gene (CASR). A 29-year-old man was referred to the outpatient department for poorly controlled hypoparathyroidism with hypocalcemia, hypomagnesemia, mild hypokalemia, excessive hypercalciuria, and a worsening eGFR under conventional therapy. He was diagnosed with hypoparathyroidism on the second day of birth. He remained inadequately controlled even after the initiation of replacement therapy with rhPTH (1-84). He was also diagnosed with chronic myelogenous leukemia (CML) at the age of 28 years and was treated with tyrosine kinase inhibitor (TKI), which further worsened the control of hypoparathyroidism. Genetic analysis was performed at the age of 31 years and revealed a change c.2486 A > G in exon 7 of the CaSR gene. This case highlights the importance of characterizing the cause of non-surgical hypoparathyroidism, including ADH1, in the differential diagnosis. ADH1 may coexist with Bartter syndrome type V, making the patient's management more challenging. To our knowledge, this is the second case in the literature with the coexistence of two rare diseases, ADH1 and CML.In CML patients treated with TKIs, serum calcium levels should be monitored and, in the case of severe hypocalcemia accompanied by low or inappropriately normal PTH, the possible existence of ADH1 may need to be investigated. [Abstract copyright: © 2025. The Author(s).]