Preterm Infants and Nephrocalcinosis

Completed

Brief Summary: Nephrocalcinosis (NC), defined as calcification of renal tissue, has been reported to occur in 7-41% of premature infants. Causes of NC are likely multi-factorial, and infants born prematurely and with very low birth weight (\<1500 gm) seem to be at the highest risk of developing NC. Recent changes in recommendations for nutrition for the preterm infant such as higher intakes of protein, calcium, and vitamin D may also play a factor in the pathogenesis of NC.

Currently, diagnosis of NC often occurs incidentally during ultrasound evaluation for other issues. Because there is no acute symptom or pattern of symptoms in the preterm population associated specifically with NC, it is possible that many cases of NC may not be diagnosed. Presently, it is impractical and costly to screen all infants for NC with renal ultrasound, therefore there is no standard of care regarding screening for NC.

NC may have long-term effects. Studies have shown that preterm infants with NC had shorter kidneys and a lower rate of tubule resorption of phosphorus (TRP) than preterm infants without NC.

This study will analyze weekly urinalysis for all enrolled subjects prospectively and then look at the incidence of NC at discharge of the enrolled subjects.

Recruitment & Eligibility

Inclusion Criteria

Infants whose gestation less than or equal to 32 weeks and/or birth weights less than 1800 gm

Exclusion Criteria

Infants with congenital abnormalities of the heart, lung, GI, or kidneys that will affect renal function.

Primary Outcome Measures

Name	Time	Method
Urinary calcium to creatinine ratio (UCa/Cr)	3 months	Beginning within the first two weeks of life, urine calcium to creatinine ratio (UCa/Cr) will be analyzed weekly through discharge and then correlated to renal ultrasound results done prior to discharge.
Urinary crystals	3 months	Beginning within the first two weeks of life, urinalysis for evidence of urinary crystallization will be analyzed weekly through discharge and then correlated to renal ultrasound results done prior to discharge.

Secondary Outcome Measures

Name	Time	Method
Serum Vitamin D levels	3 months	Serum vitamin D levels will be analyzed and compared in infants with NC against infants without NC (controls).
Vitamin D intake	3 months	Daily vitamin D intake will be recorded from participants' medical records and will be analyzed and compared in infants with NC against infants without NC (controls).
Total bone density per DXA	3 months	Whole body bone density per dual energy X-ray absorptiometry (DXA) will be done on all enrolled participants at discharge and will be compared between infants with and without NC.
Calcium intake	3 months	Daily calcium intakes will be recorded from participants' medical records and will be analyzed and compared in infants with NC against infants without NC (controls).
Protein intake	3 months	Daily protein intakes will be recorded from participants' medical records and will be analyzed and compared in infants with NC against infants without NC (controls).
Tibial bone density per tibial ultrasound	3 months	Tibial body bone density per ultrasound will be done on all enrolled participants at discharge and will be compared between infants with and without NC.

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