ESPE Abstracts

Background: The primary cause of calciopenic rickets is often vitamin D deficiency (VDD) or restricted calcium intake. It can also be caused by inactivation or resistance to vitamin D due to genetic mutations. Vitamin D genetic causes can present as early as 6 months of age in previous reports. We present here a 2-month-old baby with biochemical and radiological features highly suggestive of a metabolic bone disease likely genetic rickets. However, the baby also had significant sepsis and derangement of liver function that affected his laboratory findings.

Case Report: A two-month-old boy was born prematurely at 29 weeks gestation with symmetrical IUGR weighing 600 grams. He was privately admitted to the NICU with respiratory distress syndrome, patent ductus arteriosus, and bilateral intraventricular hemorrhage. The infant developed Staphylococcus aureus septicemia and was diagnosed with disseminated cytomegalovirus infection involving the liver. The skeletal survey was highly suggestive of severe rickets. Also, a medullary nephrocalcinosis was detected. His biochemistry revealed: Ca (2.1 mmol/l), Po4 (0.3 mmol/l), PTH (42pmol/l), ALP (1500 U/L), Vitamin D 25 OH (42 nmol/l),1,25 (OH)2 Vitamin D level (600 pmol/l, N) and GGT (530 U/L). Treatment commenced with one alpha drop and physiological calcium replacement with a dramatic improvement in PTH level as well as a decrease in ALP level. However, his GGT had also improved with the treatment of sepsis. Genetic testing and ALP isoenzymes were not feasible because of financial reasons. We discontinued one alpha and reassessed his biochemistry which remained normal. His ALP continued to improve with the resolution of sepsis. Yet, he remained with the striking radiological metaphyseal changes.

Discussion: The radiological signs associated with rickets can resemble those seen in other conditions like Schmid-type metaphyseal chondrodysplasia, hyperparathyroidism, hypothyroidism, and severe infection. VDD can always mask other presentations. Last but not least, it is difficult to differentiate between an increase of 1,25 (OH)2 Vitamin D level due to a physiological response or a pathological (genetic) cause of vitamin D-resistant rickets at such an early age of life. The radiological features could either be due to transient metaphyseal changes or a metabolic bone disease apart from genetic rickets. Moreover, the high ALP was also contributed to by the liver derangement besides nutritional rickets.

Conclusion: An unusual very early onset of severe radiological features suggestive of genetic rickets may suggest an alternative diagnosis such as metaphyseal dysplasia.