Methylxanthines increase renal calcium excretion in preterm infants.
To determine the effect of a short course of methylxanthines on renal function and on urinary calcium excretion, 20 premature neonates affected by apnea or moderate respiratory distress syndrome were randomly assigned to either a theophylline treatment or to a caffeine treatment group. The protocol included a 24-hour pretreatment study period (I) and a subsequent 24-hour period (II) following 5 days of theophylline (loading dose 5 mg/kg i.v., maintenance dose 2.5 mg/kg/12 h) or caffeine (loading dose 10 mg/kg i.v., maintenance dose 2.5 mg/kg/12 h) administration. Pre- and postxanthine treatment serum sodium, potassium, calcium and phosphorus remained stable, while serum creatinine decreased significantly (p < 0.05). Furthermore, from period I to period II, sodium urine excretion, fractional Na excretion and creatinine clearance remained statistically comparable in both study groups, along with a significant increase (p < 0.05) in calciuria, urinary Ca/creatinine and urinary Ca/Na. Predose caffeine and theophylline serum levels, assessed on the 5th day of treatment, were 12.8 +/- 1.8 and 7.9 +/- 1.7 micrograms/ml, respectively. Compared to control healthy untreated prematures, the studied premature infants showed a statistically significant increase in urine calcium excretion (10- to 15-fold), which was more evident in the theophylline group. Our data suggest further investigation to determine the long-term renal effects of methylxanthines in premature neonates, to improve assessment of the risk of nephrocalcinosis and osteopenia, in particular in association with various diuretic therapies.
Department of Pediatrics, University of Padova School of Medicine, Italy.
V
V
Zanardo
C
C
Dani
D
D
Trevisanuto
S
S
Meneghetti
A
A
Guglielmi
G
G
Zacchello
F
F
Cantarutti
D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000652:urine*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000652:urine*; D007668:Kidney / Q000187:drug effects / Q000378:metabolism*; D013806:Theophylline / Q000494:pharmacology*
D002110:Caffeine; D013806:Theophylline; D002118:Calcium