Bone Abstracts

Hypophosphatasia is an autosomal recessive rare metabolic disorder characterized by decreased bone mineralization. It can be seen in infancy, childhood or adolescence. Disease occurs due to the loss of non-specific alkaline phosphatase activity in liver, kidney and bones. There is no specific treatment. Two infants with growth retardation and failure to thrive diagnosed as infantile hypophosphatasia are presented.

Our cases had abnormalities including short stature, failure to thrive short, bowed extremities, generalised hypotonia, a small funnel chest, soft calvaria, very large fontanel, extremely wide cranial sutures, high-arched palate, low-set ears and a depressed nasal bridge. Serum alkaline phosphatase activity was 55 U/l in a 4 month-old girl and 44 U/l in a 1-month old boy respectively (Normal: 145–420 U/l). Serum calcium concentrations were 10, 4 and 10.2 mg/dl respectively (Normal: 8.9–10.3 mg/dl). Urine test for the presence of phosphoethanolamine was able to evaluated in case 2 which revealed 30 μmol/mmol of creatinine (normal child; <25 μmole/mmol creatinine).

Radiographs showed hypomineralisation of all bones, especially the calvarium, long bones and ribs; widening of sutures; and poor ossification of the calvarium. Bowing was apparent in the distal portions of both upper and lower extremities.

In this article we described two unrelated patients having a condition that can be considered as likely severe type of hypophosphatasia with high mortality.

In conclusion, hypophosphatasia must not be forgotten as an aetiological factor of abnormally low weight and/or height for age in children and alkaline phosphatase activity should be checked accurately.

Disclosure: The authors declared no competing interests.