Spontaneous resolution of bone mineral depletion in preterm infants

Article Abstract:

The bones of prematurely born infants have an abnormally low mineral content that still has not normalized by 40 weeks postconceptional age. The mineral deficit is lowest in extremely low-birthweight infants (less than 1,000 grams), and considerable (20 percent) in low-birthweight infants (less than 1,500 grams). The bones, however, undergo a change and appear to mineralize rapidly between weeks 40 and 60. To better characterize this transformation, 15 preterm infants (group P, gestational ages 25 to 34 weeks) and 17 full-term infants (group F, gestational ages 38 to 42 weeks) were studied. Forearm bone mineral content was measured by single photon absorptiometry at two times: between 38 and 44 weeks, then again between 46 and 71 weeks. A subgroup of group F, group F1, consisted of infants whose measurements were obtained between 40 and 58 weeks, close to the age of infants in group P. Results showed that members of group P were lighter and shorter than members of group F. In addition, the average bone mineral content was much lower for preterm babies at the beginning of the study (109 milligrams per centimeter versus 194.4 milligrams per centimeter). Although group P babies were younger, lighter, and shorter than group F1 babies, their bone mineral content was similar by the end of the study. The rate of mineral accretion was higher for group P than group F by a factor of 5, and higher than group F1 by a factor of 10 (groups F and F1 did not have different rates of accretion, however). Thus, although the bones of the preterm infant are undermineralized at birth, they mineralize at a very rapid rate between 40 and 60 weeks after conception. A hypothesis is proposed regarding the ways bone mineral content, weight, and body length are related. Investigations are under way to better understand the causes of the increased rate of mineral accretion in premature infants. (Consumer Summary produced by Reliance Medical Information, Inc.)

Physiological aspects, Skeletal maturity

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Bone mineral content and body size 65 to 100 weeks' postconception in preterm and full term infants

Article Abstract:

At 40 weeks after conception, preterm infants exhibit a substantial deficit in bone minerals, compared with full-term infants. In order to determine whether this deficit continues beyond the neonatal period, 36 preterm and 22 full-term infants were studied. At approximately 40 weeks after conception, both full- and preterm infants were measured in terms of weight, crown-to-heel length and bone mineral content at the mid-forearm. The preterm infants were found to be lighter and shorter than the full-term infants and to have a bone mineral content significantly less than the full-term infants. All infants were remeasured between 25 and 60 weeks later. Although there was still a significant difference in length and weight (the preterm infants were an average of 1008 grams, or about 2.2 pounds, lighter and 3.8 cm, or 1.5 inches, shorter than the full-term infants), the differential in bone mineral content was reduced significantly. The study, therefore, produced no evidence of long-term mineralization deficit 65 weeks after conception. There is a possibility that a long-term mineralization deficit may persist at skeletal sites other than the forearm. If it is established that preterm and postterm infants have substantially the same bone mineral content by approximately 60 weeks postconception, it would indicate that during the period between week 40 and week 60 there is a substantial enhancement in bone mineral content, and that this accelerated development reduces the gap between the pre- and postterm infants. (Consumer Summary produced by Reliance Medical Information, Inc.)

Infants, Growth, Composition, Infant development

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Slow release carbamazepine in treatment of poorly controlled seizures

Article Abstract:

Carbamazepine (Tegretol) is the drug of choice for treating certain types of convulsions in children, such as tonic-clonic and complex partial seizures. Previous studies have demonstrated that seizures occurred more frequently with low blood levels of carbamazepine, whereas side effects were associated with high levels of this drug. Seizures and side effects associated with carbamazepine treatment may be reduced by maintaining more steady blood levels of this anticonvulsant. A slow release preparation of carbamazepine could deliver the drug into the circulation at a delayed rate, producing less variable blood levels. The effectiveness of slow release carbamazepine in treating poorly controlled epilepsy was assessed in 33 children with epilepsy and 6 newly diagnosed patients. The slow release preparation of carbamazepine reduced the number of seizures by more than half in 12 of the 33 children, and caused fewer side effects in 10 of these patients. This dosage form of carbamazepine completely prevented seizures in three new patients. Blood levels of carbamazepine were less variable in patients taking the slow release form of the drug, compared with those of children treated with the standard form of the anticonvulsant. These results suggest that slow release carbamazepine may be beneficial in children with poorly controlled seizures. (Consumer Summary produced by Reliance Medical Information, Inc.)

Evaluation, Complications and side effects, Drug therapy, Dosage and administration, Epilepsy in children, Pediatric epilepsy, Carbamazepine

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