Bone Abstracts

Background: Acquired hypophosphataemic rickets is an unusual presentation in children and usually consequent on renal tubular damage. One of the factors important in phosphate homeostasis is FGF23. Healthy individuals maintain normal phosphate homeostasis by coupling FGF23 production with proteolytic cleavage. Iron deficiency stimulates FGF23 transcription and is a novel mechanism of FGF23 elevation. We present two children who presented with iron deficiency anaemia and hypophosphataemic rickets, which we postulate was due to elevated FGF23 levels.

Presenting problem: Two children, 5 year old male (Case 1) and 7 year old female (Case 2), presented with rachitic deformities of the lower limbs and a history of pica. Both children were stunted (HAZ score -2.59 and HAZ score -3.16) with genu valgum deformities at the knees, had frontal bossing and pallor. Radiological findings confirmed the presence of active rickets and biochemical findings confirmed hypophosphataemic rickets and anaemia in both cases (Table 1).

Clinical management: Both cases were treated with oral phosphate supplements, one alpha vitamin D and ferrous gluconate. The rickets healed and anaemia was resolving after 9 months on the above mentioned treatment and after another 9 months of ferrous gluconate only (Table 1).

Discussion: These two clinical cases highlight the association in children between iron deficiency anaemia secondary to pica and hypophosphataemic rickets. The biological intersection of iron and phosphate homeostasis through FGF23 is unknown and complex. Although, FGF23 levels were not measured in these children, it is possible that elevated FGF23 levels as a consequence of chronic iron deficiency associated with pica were responsible for hypophosphataemia and rickets. The association between pica, iron deficiency and FGF23 needs further investigation.

Disclosure: The authors declared no competing interests.