POS-748 HYPOPHOSPHATEMIA AFTER KIDNEY TRANSPLANTATION IN CHILDREN: A RETROSPECTIVE SINGLE CENTER EXPERIENCE

Abstract

Hypophosphatemia is among the common complications that are seen after kidney Transplantation (KTX). It’s noticed in the first few days in most of the KTX, particularly a well-functioning graft, and its tretment may continued many months after KTX in certain conditions. Our aim is to identify hypophosphatemia after KTX, as well its potential association with Parathyroid hormone and Vitamin D. A retrospective study of children underwent KTX between 2009-2021. We collected their Baseline demographics, type of KTX, their primary kidney diseases, time after KTX of first presentation of hypophosphatemia, initial serum phosphate level, initial levels of Parathyroid hormone, 25 OH vitamin D, Calcium, and Magnesium, time of its resolution after KTX. A 38 children underwent KTX between 2009 and 2021, their baseline demographics are shown in Table 1. A 26 (68%) of children developed hypophosphatemia with a mean of occurrence at 5 days after KTX, and range of 1 to 12 days. Early (within three days) drops in serum phosphate have been found more in living KTX, which have related to immediate functioning of the allograft, and tend to be more severe, while delayed ( more than 6 days) drops are seen more with deceased KTX, as its more likely to be associated with relative delay in graft function. The average serum phosphate level in hypophosphatemia group was 0.6 mmol/l with a range of 0.28 to 0.8 mmol/l. The mean duration of requirement of phosphate supplement after KTX was 6 months days with a range of 0.5 to 39 months. All the patients were managed with oral phosphate with a mean of dose of 650 mg/day and range of 250 mg/ day to 1500 mg/day, without the requirement of intravenous supplement except in four patients from living KTX group. The associated levels of serum Phosphate, serum Calcium, serum Magnesium, 25 OH vitamin D, and PTH for both hypophosphatemic group and normal phosphate group are shown in table 2 and 3 respectively. Children with hypophosphatemia tend to have a higher mean PTH and 25(OH)2 Vitamin D level, but the difference is not statistically significant. Table 1: Baseline Demographics Tabled 1VariableValueAge at TransplantationMean 8 yearsGenderMale 22 (58 %)Weight (Kg)22Deceased donor26 (68%)Live Related donor9 (24%)Live unrelated donor3 (8%)HLA mismatches4/6Causes of Chronic kidney diseaseCAKUT16(42%)FSGS10 (26%)CNS4 (10 %)Nephronophthesis2 (6%)Nephropathic cystinosis1 (3%)ARPKD1 (3%)Unknown4 (8%) Open table in a new tab Table 2: Hypophosphatemia group Tabled 1VariableMean (range)Phosphate (mmol/l)0.6 (0.28-0.8)Calcium (mmol/l)2.22 (1.91- 2.63)Magnesium (mmol/l)0.73 (0.52- 1.17)Alkaline Phosphatase (U/l)194 ( 51- 713)Parathyroid Hormone (Pg/ml)587 (34 - 1565)25 (OH)2 Vitamin D (nmol/l)53 ( 7- 110) Open table in a new tab Table 3: Normophosphatemia group Tabled 1VariableMean (range)Phosphate (mmol/l)1.22 (0.9-1.64)Calcium (mmol/l)2.30 (2.15- 2.78)Magnesium (mmol/l)0.75 (0.55- 1.03)Alkaline Phosphatase (U/l)176 ( 55- 297)Parathyroid Hormone (Pg/ml)520 (113 - 1354)25 (OH)2 Vitamin D (nmol/l)43 ( 7- 82) Open table in a new tab Hypophosphatemia is a commonly seen after kidney transplantation particularly those with immediately functioning graft, higher PTH is a known potential contributory factor but that was observed partly in our cohort. our result should be interpreted with caution because of small sample size and retrospective design, so prospective large sample study can delineate this area more clearly.