ESPE Abstracts

Background: Bartter syndrome represents a rare severe condition, autosomal recessive, corresponding to several genes, characterized by an illness of the renal ascending branch of the handle of Henle. Only 15 cases of BSHPT have been communicated, either in publications or orally, but none presented such severe bone manifestation as ours.

Objective and hypotheses: To present bone features of two patients suffering from severe BHSPT, so as the therapeutic attempts.

Results: Two female patients are described, the first one bearing an homozygous mutation of gene SLC1.2A1 coding for NKCC2 ion channel and the second one a composite heterozygous mutation of gene BSND, coding for Barttin protein. Both presented hydramnios and severe intrauterine growth retardation without catch up. At the age of 6 years and a half, patient number one suffered from non- inflammatory, painful and disabling arthritis of elbows, knees and feet. Patient number 2 was affected by two pyelonephritis episodes. Both shared different complications: limb deformations, articular stiffness and worsening dwarfism, resulting into most severe handicap; nephrocalcinosis; extended bone demineralization, sub-periostal resorption and bone deformations, so as signs of chronic arthropathy and the absence of synovitis at-X-ray exams; biologically, hypercalcemia (up to ~120 mg/l), hypercalciuria, high parathyroid hormone levels (up to ~1500 pg/ml in number one, ~270 pg/ml in number 2). Different treatments were tried: cinacalcet, a calcium-sensing receptor agonist (30 mg/d), which partially corrected hyperparathyroidism in number one and had to be stopped, because of major hypocalcemia in number 2, intravenous biphosphonates (pamidronate and zoledronate), growth hormone, which failed on growth and even surgical ablation of two parathyroid glands in number one, without any success. Several mechanisms of BSHPT have been mentioned, most appropriately an autonomous development of hyperparathyroidism reactive to hypercalciuria.

Conclusion: In antenatal Bartter syndrome, parathyroid hormone should be monitored early, to assume early bone-protective measures.