ESPE2024 Poster Category 2 Bone, Growth Plate and Mineral Metabolism (31 abstracts)
Hereditary hypophosphatemic rickets with hypercalciuria: a rare disorder not to be forgotten about
Matteo Pontone 1,2 , Alesssandro Barbato 1,2 , Matteo Cerutti 1,2 , Nicolò Chiti 1,2 , Laura Corbelli 1,2 , Alessio Rossi 1,2 , Sara Soldovieri 1,2 , Eugenio Trinati 1,2 , Giovanna Municchi 2 & Stefano Stagi 1,2
1Department of Health Sciences, University of Florence, Florence, Italy. 2Diabetology and Endocrinology Unit, Meyer Children’s Hospital IRCCS, Florence, Italy
Background: Hereditary hypophosphatemic rickets with hypercalciuria (HHRH) is a rare autosomal recessive disorder characterized by rickets, muscle weakness, bone pain, nephrocalcinosis or nephrolithiasis. It is caused by mutation in SLC34A3 gene, encoding for renal sodium-phosphate cotransporter IIc (NaPi-IIc).
Case: A patient aged 10 years came for evaluation for bone pain at lower limbs. He was born at full term from normal pregnancy, with weight 3700 g and length 52 cm. Pathological history: valgism of the knees for which he had X-ray of the lower limbs with dysmorphic appearance of femoral and tibial epiphyses. Family history: moulting. At clinical evaluation: height 135.2 cm (-1,16 SDS WHO growth charts), weight 42.8 kg (+0.5 SDS WHO growth charts), prepubertal. Blood tests were performed (table - T0), revealing severe vitamin D deficiency, increased alkaline phosphatase (AF) and hypophosphoremia. Cholecalciferol replacement therapy was indicated.
| T0 | T1 | T2 | |
| Ca (mg/dl) | 4.1 | 4.7 | 4.3 |
| P (mg/dl) | 2.1 (↓) | 4.7 | 3.7 (↓) |
| Mg (mg/dl) | 2.3 | 2 | 2.1 |
| AF(UI/l) | 1392 (↑) | 920 (↑) | 1021 (↑) |
| 25-OH-D (ng/ml) | <4 (↓) | 49 | 30 (↓) |
| 1-25-OH-D (pg/ml) | --- | 369 (↑) | 181 (↑) |
| T,D.PTH (pg/ml) | 50.7 | 6.83 (↓) | 9.94 (↓) |
| Urinary calcium (mg/24 h) | --- | 349.8 (↑) | --- |
| Urinary phosphate (mg/24 h) | --- | 433.4 | --- |
| FGF-23 (pg/ml) | --- | 7.3 | 9.1 (↓) |
Blood tests were checked 1 month (table - T1) and 6 months (table – T2) after starting therapy. Abdominal ultrasound was performed, but no images of calcifications were found. Due to the significant rise in AF, persistently low parathormone (PTH) (despite eucalcemia), hypophosphoremia, hypercalciuria and increased 1-25-OH-D, bone mineral density was assessed through Dual-Energy X-ray Absorptiometry (DXA), finding a lumbar Z-score (L1-L4) of -1.2, suggestive of reduced bone mineral density. Genetic investigation was therefore carried out on the patient and his parents, with a DNA finding of variants c.497 G>A, p.(Gly166Asp) and c.1446_1455del, p.(Arg483Glyfs*81) in the SLC34A3 gene. Analysis of the parents' DNA showed the presence of the first variant in heterozygosity on the paternal DNA, and the second variant in heterozygosity on the maternal DNA. A diagnosis of autosomal recessive hypophosphatemic rickets with hypercalciuria was made. Vitamin D supplementation was discontinued and phosphorus supplementation was started.
Conclusion: At debut, severe hypovitaminosis D might suggest the diagnosis of deficient rickets; however, in the presence of laboratory parameters not improving despite adequate replacement therapy it is necessary to consider alternative diagnoses. Specifically, increased 1-25-OH D and hypercalciuria should immediately raise suspicion for HHRH.
Article tools
My recent searches
My recently viewed abstracts
Authors
ESPE Abstracts
© Bioscientifica 2024 |
Privacy policy |
Cookie settings
BiosciAbstracts
Bioscientifica Abstracts is the gateway to a series of products that provide a permanent, citable record of abstracts for biomedical and life science conferences.
Find out more