Sannapaneni Shilpa, Krishnasamy Sathya, Reyes Monica, Jüppner Harald, Lederer Eleanor D
Baylor University Medical Center - Dallas, Dallas, Texas.
Department of Medicine, University of Louisville, Louisville, Kentucky.
Am J Kidney Dis. 2025 Aug;86(2):272-275. doi: 10.1053/j.ajkd.2025.01.019. Epub 2025 Mar 17.
Hypocalcemia is an uncommon electrolyte abnormality. We evaluated a young woman with episodes of recurrent symptomatic hypocalcemia, which had started in her late teens. She was hypertensive and laboratory evaluation revealed elevated parathyroid hormone, elevated phosphate, and decreased renal phosphate excretion along with low ionized calcium levels. Her renin and aldosterone levels were elevated. While the response to treatment with calcium and 1,25(OH) dihydroxyvitamin D was modest, her laboratory values and symptoms improved significantly during pregnancy and then recurred post-delivery. Based on clinical and laboratory features, we made a diagnosis of pseudohypoparathyroidism type Ib (PHP1B). Her genomic DNA revealed broad methylation changes at the GNAS locus, which encodes the α-subunit of the stimulatory G protein (Gα), without evidence for a deletion or duplication, consistent with PHP1B. Analyses of several microsatellite markers on chromosome 20 performed on our patient and her parents provided no evidence for paternal uniparental isodisomy/heterodisomy of chromosome 20q13.3 (patUPD20q). The approach to hypocalcemia; classification, clinical features, and genetic/epigenetic basis for pseudohypoparathyroidism; alterations of mineral metabolism in PHP1B and pregnancy; and implications for the high renin and aldosterone levels and hypokalemia are discussed.
低钙血症是一种不常见的电解质异常。我们评估了一名年轻女性，她自十几岁后期开始出现反复发作的症状性低钙血症。她患有高血压，实验室检查显示甲状旁腺激素升高、磷酸盐升高、肾磷酸盐排泄减少以及离子钙水平降低。她的肾素和醛固酮水平升高。虽然钙和1,25(OH)二羟维生素D治疗反应一般，但她的实验室检查值和症状在孕期显著改善，产后复发。基于临床和实验室特征，我们诊断为Ib型假性甲状旁腺功能减退症（PHP1B）。她的基因组DNA显示在编码刺激性G蛋白（Gα）α亚基的GNAS基因座存在广泛的甲基化变化，无缺失或重复证据，符合PHP1B。对我们的患者及其父母进行的20号染色体上几个微卫星标记的分析未提供20q13.3染色体父系单亲二体/异二体（patUPD20q）的证据。本文讨论了低钙血症的处理方法、假性甲状旁腺功能减退症的分类、临床特征以及遗传/表观遗传基础、PHP1B中矿物质代谢的改变和妊娠情况，以及高肾素和醛固酮水平及低钾血症的影响。
