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Abstract: SA-PO520

Rare Co-Existence of Osteogenesis Imperfecta and Familial Renal Phosphorus Wasting

Session Information

Category: Fluid‚ Electrolyte‚ and Acid-Base Disorders

  • 1002 Fluid‚ Electrolyte‚ and Acid-Base Disorders: Clinical

Authors

  • Abid, Sidrah, Albany Medical Center, Albany, New York, United States
  • Hongalgi, Krishnakumar D., Albany Medical Center, Albany, New York, United States
  • Beers, Kelly H., Albany Medical Center, Albany, New York, United States
Introduction

Osteogenesis imperfecta (OI) is a severe disease with a wide spectrum of presentations depending upon the genetic abnormality. Known as a pure collagen abnormality, co-existence with an electrolyte abnormality such as hypophosphatemia is rarely reported. It could be indicative of multiple genetic abnormalities and may have worsening effect on overall prognosis.

Case Description

Our patient is a 35-year-old female with past medical history of severe scoliosis, blue eyes, and OI diagnosed at birth. Patient was referred to nephrology office for low serum phosphorus level after extensive work up done by endocrinology was non-revealing. Urine dipstick was negative for glucose, protein, blood, ketones, and bilirubin. Renal panel was unremarkable except serum phosphorus level of 1.7 mg/dl. Remaining labs showed serum magnesium 2.2 mg/dl, intact parathyroid hormone 27 pg/ml (15-65pg/ml), thyroid stimulating hormone (TSH) 1.850 uIU/ml (0.450-4.5), 24-hour urine phosphorus 0.7gm/day, 24-hour urine calcium 26 mg/day, 24- hour urine creatinine 1.2g/day, urine dipstick was negative for glucose and proteins. Patient was started on calcitriol and oral phosphate supplements. In view of elevated urine phosphorus excretion in the setting of hypophosphatemia, genetic testing was obtained that reported a variant of ALPL gene and SLC34A4 gene. The ALPL gene variant is associated with autosomal recessive and autosomal dominant hypophosphatemia. The SLC34A3 gene variant is associated with autosomal recessive hereditary hypophosphatemic rickets with hypercalciuria. Hence, our patient was kept on oral phosphorus and calcitriol supplements with close monitoring of serum electrolytes.

Discussion

Osteogenesis imperfecta is a disease with severe clinical manifestations and while treatment options are only limited to symptomatic management, coexistence of another electrolyte abnormality further worsens the prognosis. These patients should undergo timely genetic counselling along with a multidisciplinary approach for management.

TESTRESULTReference values
Fibroblast growth factor-23102 RU/ml< 180 RU/ml
ALPL geneHeterozygous 
SLC34A3 geneHeterozygous 
25- hydroxy vitamin D29.0 ng/ml30.0-100.0