Bone Abstracts

Background: Transient hyperphosphatasemia of infancy and early childhood (THI) is a benign, usually accidentally detected condition characterized by transiently increased activity of serum alkaline phosphatase (S-ALP), its bone or liver isoform, in children under five years of age, without signs of metabolic bone disease or hepatopathy. When encountered in a child with either chronic bone, liver or kidney disease, THI might concern the physician. We present a patient with urolithiasis and THI.

Case presentation and clinical management: 13-months old boy with a complicated perinatal history (severe prematurity – 26th week of gestation, respiratory distress syndrome, reanimation, neonatal sepsis, pneumonia, artificial ventilation) resulting in bronchopulmonary dysplasia and osteopathy of prematurity, was hospitalised because of hematuria. Abdominal ultrasound revealed renal stones in each kidney, diameter, 3 mm on the left and 6 mm on the right, respectively. The serum values of blood urea nitrogen (BUN), creatinine, potassium(S-K), sodium(S-Na), calcium(S-Ca), phosphate(S-P), magnesium(S-Mg), alanin-aminotransferase(S-AST), apartate-aminotransferase(S-ALT) were all within normal reference range, same as urinary concentrations of Ca, P, Mg and urinary calcium/creatinine ratio (U-Ca/U-cr). S-ALP was 34 μkat/L (normal 2.5–9.5 μkat/l). Wrist X-ray was normal without any signs of rickets. Hematuria resolved within 3 days. As there were neither laboratory or clinical signs of liver or bone disease, THI was considered as the most likely diagnosis. The boy was checked 28 days.later, and at that time the S-ALP dropped to normal value 9.2 μkat/l.

Discussion: Patient with bilateral nephrolithiasis and a history of severe prematurity presented with high S-ALP, initially suggestive of disturbed bone metabolism. However, the normal values of S-Ca,P,Mg,PTH,U-Ca/U-cr and normal wrist X-ray ruled out this possibility and pointed to the diagnosis of THI, which was further confirmed by the normalisation of S-ALP within one month. The present nephrolithiasis was considered as a result of previous hypercalciuria in osteopathy of prematurity, that has already resolved without causal relationship to transiently increased S-ALP. There were no further increases in S-ALP and the patient, who is currently 25 months old, remains stable. THI is a benign condition with good prognosis. Children with THI should be spared from unnecessary early diagnostic procedures and therapeutic interventions.

Disclosure: The authors declared no competing interests.