Nephrocalcinosis in very low birth weight infants: a single center experience.

OBJECTIVES: To determine the incidence and risk factors of nephrocalcinosis in very low birth weight infants. MATERIAL AND METHOD: Medical records of inborn infants with gestational age less than 32 weeks or birth weight less than 1,250 grams were collected and analyzed. All infants were born at King Chulalongkorn Memorial Hospital in the year 2003. At least one renal ultrasonographic scan was performed on every infant as a routine screening before discharge. Data on family history of renal stone, gestational age, birthweight, infant's illness,fluid intake during the first 6 weeks of life, duration of respiratory support, medications, serum calcium, phosphate and alkaline phosphatase level, duration of parenteral nutrition, length of hospitalization, ultrasonographic findings and related renal morbidity were collected and compared between the groups of infants with and without nephrocalcinosis. RESULTS: Thirty six infants were included in the present study. Fourteen had abnormal ultrasound scans compatible with nephrocalcinosis giving an overall incidence of 38.9%. Factors associated with nephrocalcinosis included severity of respiratory illness, PDA, oxygen dependency, furosemide therapy, and fluid restriction. Urinary tract infection was the renal morbidity found in 3 infants (21.4%). Nephrocalcinosis was resolved in one out of 7 infants who had repeated renal ultrasound scan at about 2 months after the first scan. CONCLUSION: Very low birth weight, preterm infants have a risk of developing nephrocalcinosis especially those with severe respiratory illness and prolonged use of furosemide. Infants at risk should be screened with renal ultrasonography prior to discharge from the hospital.

Antibody response to hepatitis B immunization in infants born to HIV-infected mothers.

OBJECTIVES: To determine the antibody response of hepatitis B immunization begun at birth in HIV-1 exposed infants. DESIGN: Prospective, clinical trial. SITE: King Chulalongkorn Memorial Hospital, Bangkok, Thailand. MATERIAL AND METHOD: Seventy six infants born to HIV-1 seropositive mothers, who were not hepatitis B carriers, received three 10 microgram doses of recombinant DNA hepatitis B vaccine (Engerix B, Smith Kline, Belgium) in a 0, 1 and 6 month schedule. The first dose was given at birth. Serum hepatitis B surface antibody (Anti -HBs) was measured at age 3, 9 and 12 months. Anti-HBs levels were determined by enzyme-linked immunoassay using the commercial kits (AUSAB EIA diagnostic kits, Abbott Laboratories, Chicago, USA) Antibody titer > or = 10 mIU/ml was defined as seroconversion. HIV infection was diagnosed by a positive test of HIV antibody at age > or = 18 months and/or by positive test of HIV polymerase chain reaction at age > or = 3 months. RESULTS: There were 14 HIV-1 infected (group 1) and 62 HIV-1 non infected (group 2) infants enrolled in this study. Anti-HBs titers of group 1 infants were significantly lower than those of groups 2 infants at both 3 and 6 months after the 3rd dose of vaccine, (Mann Whitney U test, p=0.019 and 0.001 respectively). Ten infants in group 1 and 57 infants in group 2 had anti-HBs titer > or = 10 mIU/ml. Their peak antibody titers were also noted at both 3 and 6 months after the 3rd dose of vaccine. Seroconversion rates were 71.4 per cent and 91.9 per cent in group 1 and 2 infants respectively, (p<0.05). Among the infants who had blood tests performed at age 12 months or 6 months after the 3rd dose of vaccine, anti-HBs titers declined in approximately 50 per cent of both groups of infants. There was a significantly higher percentage of seroconverters in group 1 who lost their protective titers than those in group 2, (p<0.001). CONCLUSION: The results in this study suggested that HIV-1 infected infants have poor antibody response to hepatitis B immunization and the protection was less durable. A fourth dose of vaccine at 6 months after the 3rd dose may be necessary.