P-18 Dent's Disease as a rare cause of rickets

Abstract

Abstract Introduction Dent's disease is a rare recessive X-linked disorder characterized by hypophosphatemia, hematuria, proteinuria, hypercalciuria, nephrocalcinosis, and progressive renal failure. The majority of cases are caused by mutations in the CLCN5 or OCRL genes. The primary mechanisms of rickets in Dent's disease are a deficiency in phosphate absorption in the proximal tubules of the kidney and an increase in urinary calcium excretion. In order to draw attention to this rare disease, we present a patient diagnosed with Dent's disease while being evaluated for hypophosphatemic rickets. Clinical Case A 23-year-old male patient with Dent's disease was referred to an adult endocrinology clinic for follow-up after a CLCN5 mutation was identified during an examination for hypophosphatemic rickets and proteinuria at the age of three. Since the age of 18, he has been diagnosed with chronic kidney disease. At the age of 19, he has a history of hospitalization for osteomyelitis. No history of fracture. In his family history, both of his parents were cousins, that have short stature and Dent's disease mutation was found to be heterozygous. Both cousins had hypophosphatemic rickets diagnosis. On physical examination, he was mobile, 155 cm tall, weighed 55 kilograms, had bilateral genu valgum, and other system examinations revealed no pathology. The patient was taking 500 mg of phosphate three times per day in addition to 0.5 microgram of calcitriol. In laboratory evaluation, creatinine was 3.11 mg/ dL, GFR was 26 ml/min, PTH was 118 pg/mL, ALP was 82 IU/ml, phosphorus was 3.44 mg/ dL, and calcium was 10 mg/dL. 24-hour urine calcium: 195 mg/day; osteocalcin: 188 ng/mL; beta-crosslaps: 2 ng/mL. It was determined to be high-turnover chronic kidney disease-bone disorder. Urinary ultrasonography showed bilateral kidney diameters decreased and parenchymal thickness thinned, bilateral kidney echoes increased, and bilateral medullary nephrocalcinosis with high echogenicity and calcifications. Cataract and basal ganglia calcification were not detected. Dual Energy X-Ray Absorbsiometry evaluation revealed that the L1-L4 BMD: 0.915 gr/cm2 Z score: -1.1 and the femoral neck BMD: 0.614 gr/cm2 Z score: -3.1 were lower than anticipated for age. The patient's calcitriol dosage was reduced to three times per week after PTH suppression. Since the serum ALP concentration was normal, the oral phosphorus dose was not altered. A limited sodium diet was suggested for the patient. The patient with bilateral nephrocalcinosis was referred to the nephrology clinic for further evaluation. Conclusion Patients diagnosed with rickets should also be mindful of Dent's disease, which must be closely monitored alongside nephrology.Figure 1.Bilateral knee radiograph of the patient