P2A352: Serum Phosphorous Dynamics in Children with Diabetic Ketoacidosis

Background: Objectives of this study were to assess dynamics of serum phosphorus (P) in children during therapy for diabetic ketoacidosis (DKA). We evaluated factors associated with nadir serum P (lwstP), the time to development of hypophosphotemia (hypophos), length of hypophos, and length of hospital stay (LOS).

Methods: Children 1-17 years of age hospitalized for DKA between January 1 to December 31, 2022 were included: Age, sex, years with diabetes, hemoglobin A1C (A1C), initial (i) blood pH (ipH), glucose (iG), serum electrolytes including phosphorus (iP), calcium (iCa) and Magnesium (iMg) were recorded. LwstP, and nadir serum potassium (lwstK) and the numbers of hours to reach lwstP (lwstPhrs) and lwstK (lwstKhrs) following initiation of therapy were documented. Hypophos was defined as the serum phosphorus level below the lower limit for age and gender. Severe hypophosphatemia was defined as a level < 1.5 mg/dL regardless of age. Cardiac arrhythmias were defined via bedside continuous monitoring of lead II of the electrocardiography (EKG).
Data are presented as mean +/- SD. t test used for continuous data and chi-squared for discrete data. Stepwise regression analysis was performed to evaluate for variables most closely associated with lwstP, lwstPhrs, and length of hypophosphetemia (lngthhypo). A p-value < 0.05 was considered statistically significant.

Results: 95 patients (64% male, age 12.2 +/- 4.8 yrs, years with diabetes: 3.8 +/- 3.1 with A1/C 12.9 +/- 2%) experienced 101 episodes of DKA with the following initial parameters: ipH 7.1 +/- 0.1, iG 468 +/- 178 mg/dL, iphos 5.5 +/- 1.8 mg/dL, iNa 133 +/- 4.7 mEqL, iK 5+/-0.75 mEq/L, iCl 99 6.9, bicarbonate 8 +/-3.8 mEq/L, iBUN 22 +/- 12, iCr 1.5 +/- 2 mg/dL and iMg 2.2 +/-0.40. Initial serum P was elevated (5.5 +/- 1.8 mg/dL), declined during therapy and reached a nadir at 12 +/- 8 hrs into therapy. Initial serum P correlated with iK (r=0.52, p< 0.05), iCr (r=0.61, p< 0.01) and iMg (r=0.52, p< 0.01). Hypophos for age and gender occurred in 62 cases (61.4%), however, severe hypophos occurred only in 3 cases (3%) and non of these 3 cases developed arrhythmias. patients with hypophos had a lower ipH (7.07 +/- 0.1 vs. 7.14 +/- 0.06, p< 0.001) and a lower nadir potassium (3.4 +/- 0.4 vs 3.6 +/- 0.33, p < 0.04) compared to patients without hypophos. Variables that had the most impact on nadir serum P included ipH (b=3.1,p < 0.001), female gender (-0.3,p=0.03) and iCalcium (b=0.3,p=0.006). Length of time to development of hypophos was affected by ipH and iphosphorus. Length of hypophosphatemia was associated with a longer LOS.

Conclusion: Hypophosphetemia occurs commonly during therapy for DKA in children. Most children are asymptomatic and severe hypophosphetemia is rare in this clinical setting.