Searchable abstracts of presentations at key conferences in endocrinology
Endocrine Abstracts (2007) 14 P451

ECE2007 Poster Presentations (1) (659 abstracts)

Familial hypocalciuric hypercalcemia: mutation in the calcium sensing receptor gene

Sandra Paiva 1 , Cristina Ribeiro 1 , Luisa Barros 1 , Leonor Gomes 1 , Miguel Melo 1 , Joana Guimarães 1 , Margarida Venâncio 2 , Jorge Saraiva 2 & Manuela Carvalheiro 1


1Serviço de Endocrinologia, Diabetes e Metabolismo dos Hospitais da Universidade de Coimbra, Coimbra, Portugal; 2Serviço de Genática Médica do Hospital Pediátrico de Coimbra, Coimbra, Portugal.


Familial hypocalciuria hypercalcemia (FHH) is an autossomal dominant condition caused by mutations in the calcium sensing receptor gene. It is characterized by moderate hypercalcemia, with normal or slightly elevated PTH levels and hypocalciuria secondary to the increased calcium reabsorption at the distal tubule level.

We present a case report of a 16 year old patient, who was referred to our department at the age of 14 because of obesity (BMI: 36.9 K/m2). Initial biochemical evaluation revealed hypercalcemia (11.1 mg/dL – Normal range: 8.4–10.4) and normal albumin levels. These findings prompted further evaluation, with the following results: PTH: 98/92 pg/ml (N: 9–72), urine 24 hour calcium levels: 92 mg/24 h (N: 100–300) and cervical ultrassonography revealed a small 5 mm nodular structure. One could however not exclude that this was in fact parathyroidal tissue. Cintigraphy with Sestamibi did not show abnormal fixation. Given these results, further study was pursued in 1st degree relatives, and it was found that the father and one of the siblings had slight hypercalcemia and hypocalciuria.

Genetical analysis of the propositus undercovered a heterozygous mutation in R648X of CASR gene (located in the long arm of chromossome 3).

This case underscores the relevance of genetical characterization in disturbances of calcium metabolism, in particular in differential diagnosis of hyperparathyroidism and FHH, which is often difficult in light of conventional assessment. Accurate diagnosis is essential for correct therapeutic management, which stresses the need for genetical analysis in current clinical practice.

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