ESPE Abstracts

Aim: The pathophysiology of developing hypophosphatemia in children with diabetic ketoacidosis (DKA) has not been sufficiently elucidated. Fibroblast Growth Factor 23 (FGF23) is a hormone that causes phosphate excretion from the kidneys. The increase of FGF23 in children with DKA may explain the pathophysiology of hypophosphatemia in these children. The aim of our study was to investigate the effect of serum FGF23 on serum phosphorus level in children with DKA.

Materials and Methods: Our study included 30 patients with DKA. Data including age, gender, height and body weight measurements were recorded. Blood gase parameters including pH, PCO₂, and HCO₃ and serum BUN level were measured at the beginning of DKA treatment and at the lowest serum phosphorus level. Biochemical parameters including serum Cr, Ca, P, Mg, ALP, PTH, intact FGF23 (I-FGF23) and c-terminal FGF23 (C-FGF23) levels and tubular phosphate reabsorption (TPR) ratio were determined at the beginning of DKA treatment, at the lowest serum phosphorus level, and at the time of discharge.

Findings: The study was completed with 18 (%60) old and 12 (%40) new cases. The mean age of the patients was 140 ± 57 months. The mean serum Cr, Ca, P, Mg and ALP levels at the lowest serum phosphorus level compared to the onset of DKA treatment were significantly decreased (P=0,000, P=0,002, P=0,000, P=0,000 and P=0,000, respectively) while TFR ratio was significantly increased (P=0,000). The mean serum Cr level at the time of discharge compared to the lowest serum phosphorus level decreased significantly (P=0,008) while serum Ca, P, Mg, PTH, I-FGF23 and C-FGF23 levels and TFR ratio were significantly increased (P=0,001, P=0,000, P=0,002, P=0,015, P=0,02, P=0,007 and P=0,001, respectively). Serum P level was negatively correlated with pH and HCO₃ levels (r=-0,495; P=0,000 and r=-0,383; P=0,003, respectively) while it was positively correlated with serum BUN, Cr and C-FGF23 levels and TPR ratio (r=0,634; P=0,000, r=0,487; P=0,000, r=0,230; P=0,047, and r=0,528; P=0,000, respectively). Serum Mg level was negatively correlated with pH and HCO₃ levels (r=-0,359; P=0,005 and r=-0,236; P=0,05, respectively) while it was positively correlated with serum PTH level (r=0,328; P=0,011).

Conclusion: The results of our study suggest that the improvement in alkalosis and decrease in TPR ratio during DKA treatment are effective factors in the development of hypophosphatemia, whereas I-FGF23 and C-FGF23 do not have any role in the development of hypophosphatemia.