Spontaneous resolution of bone mineral depletion in preterm infants.

Fifteen preterm infants and 17 born at full term whose gestational ages ranged from 25 to 34 weeks and 38 to 42 weeks, respectively, were examined initially at postconceptional ages ranging from 38 to 44 weeks and subsequently at 46 to 71 weeks. Each examination included measurement of bone mineral content of the mid-forearm by single photon absorptiometry. For the preterm group, the mean (SD) value of bone mineral content at the first examination was 109.0 (27.6) mg/cm and was significantly lower than the corresponding value of 194.4 (19.6) mg/cm for the whole full term group. The mean subsequent rate of mineral accretion in the preterm group was 8.70 (4.60) mg/cm/week, the mean individual duration of observation being 9.7 weeks. Rate of mineral accretion for the full term group was independent of the duration of observation and averaged 1.60 (2.20) mg/cm/week. The difference between mean values of rate of mineral accretion in the preterm and full term groups was highly significant. Our results show that there is a phase of rapid mineral accretion starting at 40 weeks' postconception in preterm infants that substantially reduces the perinatal mineralisation deficit.

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

A total of 36 preterm and 22 full term infants were weighed and measured at 65 to 100 weeks' postconception. It was found that the preterm infants were on average significantly lighter by 1008 g and shorter by 3.8 cm than those born at full term. Despite the smaller size of preterm infants, mean values of bone mineral content in the mid-forearm were not significantly different between the two groups. In contrast, near 40 weeks' postconception the mean bone mineral content observed in 35 of the preterm infants was significantly smaller than that observed in eight of the full term infants. Our results suggest that there is a phase of rapid mineral accretion between 40 and 60 weeks' postconception. This 'catch up' in mineral accretion reduces the perinatal mineralisation deficit that might otherwise persist into childhood.

Duplication of distal 17q from a maternal translocation: an additional case with some unique features.

A female with multiple dysmorphic features was found to have an unbalanced karyotype with duplication of the distal long arm of chromosome 17 and deletion of the terminal region of the short arm of chromosome 12. This was derived from a reciprocal translocation in the mother, 46,XX,t(12;17)(p13.3;q23). Clinical findings are presented and comparison with other reported cases of distal 17q duplication shows several unique features in our case.

Bone mineral accretion rate and calcium intake in preterm infants.

Thirty six preterm infants (20 boys) of 25 to 32 weeks' gestation were observed from birth to around 40 weeks' postconception. When oral feeding became possible, nine received mother's own breast milk (group B), 15 formula feed (group F), and 12 formula feed supplemented with calcium (5 ml 10% calcium gluconate/100 ml feed) and phosphorus (0.5 ml 17% potassium phosphate similarly) (group S). All received a daily supplement of 400 IU vitamin D. Intakes of calcium, phosphorus, vitamin D, energy, and fluid volume were recorded. When oral feeding started, and near 40 weeks' postconception, bone mineral content of the forearm was measured by photon absorptiometry; weight and crown-heel length were also measured. After logarithmic transformation of the measurements, there were no significant intergroup differences between the mean rate constants for weight or crown-heel length describing growth during the observation period. The mean rate constant for mineral accretion (M) was significantly higher in group S than in both the others. Pooling all data, M was significantly correlated with calcium intake but not with any other variable. Mineral supplementation of feed can reduce but not cure osteopenia of prematurity.

Osteopenia in extremely low birthweight infants.

Fifteen extremely low birthweight (ELBW) white infants (those weighing 1000 g or less) were observed at birth, within eight weeks of birth and near 40 weeks postconception. On the second and third occasions, weight, crown-heel length, and bone mineral content of their forearms were measured. Fifteen infants born at full term on whom similar measurements were made soon after birth acted as controls. Between 32 and 39 weeks the median weight of ELBW infants increased from 970 g to 1850 g and crown-heel length from 35.7 cm to 41.0 cm. There was no evidence, however, of bone mineral accretion in the measurement region; initial and final median measurements of bone mineral content were 76 mg/cm and 86 mg/cm, the median individual difference being only 4 mg/cm with an interquartile range of 25 mg/cm. Median weight, crown-heel length, and bone mineral content of the control group were 3270 g, 50.6 cm, and 196 mg/cm, respectively. Compared with the controls, ELBW infants at 39 weeks were a median (interquartile range) of 1420 (525) g lighter, 9.9 (3.9) cm shorter, and had a bone mineral content deficit of 108 (32) mg/cm. In terms of weight and crown-heel length ELBW infants at 39 weeks were comparable with infants born and observed at 32 weeks' gestation; compared with these infants the bone mineral content deficit in the ELBW group was about 33%.

The relationship between theophylline, caffeine and heart rate in neonates.

Plasma theophylline and caffeine levels were measured in neonates receiving aminophylline for apnoea. Significant levels of caffeine were present in neonates with high plasma theophylline levels and particularly in those children who had been on theophylline for 6 days, or more. Caffeine levels in plasma decreased slowly compared to theophylline. Tachycardia did not occur in any infants even at theophylline values greater than 20 mg/L. For theophylline concentrations above 10 mg/L there was no relationship between heart rate and drug level. Heart rate alone cannot be used to predict toxic drug levels, and high drug levels will not necessarily cause tachycardia.

Mineral accretion in the human fetus.

Bone mineral content of the mid forearm was measured by photon absorptiometry in 73 white singletons (36 boys, 37 girls) born between 18 and 43 weeks' gestation. Results obtained within two weeks of birth for liveborn infants were used to establish bone mineral deposition curves approximating normal in utero development. Results for stillborn infants indicated a retardation of bone mineralisation relative to liveborn infants. This has important implications concerning previous estimates of daily calcium needs for preterm infants. Eleven liveborn Asian singletons and nine pairs of white twins were examined similarly. With respect to bone mineral content, weight, and crown-heel length, Asians with gestational ages over 35 weeks and twins were closely comparable with their white singleton peers. Asians under 35 weeks tended to be smaller than white singletons of comparable age.

Mineral content of rib bone in infant deaths.

The mineral content of rib bone in infants who died unexpectedly was similar to that among those who died after acute illnesses, and it was significantly associated with both crown to heel length and age. In those dying from chronic illnesses it was lower than in the other two groups.

Bone mineral content in bronchopulmonary dysplasia.

Fourteen preterm infants who developed bronchopulmonary dysplasia diagnosed radiologically were compared with a group of similar infants who did not. The two groups were of comparable maturity and birth weight. The clinical histories indicated that those infants with bronchopulmonary dysplasia had had longer periods of supplemental oxygen, more frequent treatment with dexamethasone, and a higher mean total dosage of frusemide. Bone mineral content in the mid-forearm was measured by photon absorptiometry at or near the postconceptional age of 40 weeks in all cases; no significant difference was found between the two groups, although both were severely undermineralised when compared with infants born at full term. In both groups mean daily calcium intake (about 70 mg/kg/day) was about half the daily intrauterine accretion of calcium.

Multiple sulphatase deficiency presenting at birth.

A new case of multiple sulphatase deficiency with onset at birth is described. The patient had many dysmorphic features and hydrocephalus, similar to one other case with early onset described in the literature. The new patient differed from the other case in having chondrocalcificans congenita, heart abnormalities and an abnormal fold of tissue present between the laryngeal inlet and the oesophagus. Excessive mucopolysacchariduria was present and there was profound deficiency of all sulphatases examined in plasma, leucocytes and cultured skin fibroblasts.

Osteopenia of prematurity.

Bone mineral content of the forearm was measured by photon absorptiometry in 17 preterm infants at a postconceptional age of 40 weeks. Radiographs of the forearm were assessed by Koo's method and plasma alkaline phosphatase activity was also measured at this time. Bone mineral content was significantly but weakly correlated with Koo score and was not significantly correlated with alkaline phosphatase activity. Neither of these two commonly used investigations accurately predicts the presence of underlying bone disease. Compared with 15 full term infants the preterm infants had significantly lower values of bone mineral content, palpated ulnar length, and crown-heel length. After adjusting for weight and ulnar length the preterm group still had a significantly lower mean value of bone mineral content than the full term group. Accurate diagnosis of osteopenia of prematurity requires photon absorptiometry, with bone mineral content assessed relative to body weight or ulnar length.

Measurement of bone mineral content in the human fetus by photon absorptiometry.

A photon absorptiometer designed to measure the bone mineral content (BMC) of the radius and ulna in premature or term babies was used to examine 34 forearm specimens obtained from 25 male and 9 female babies dying before or up to 13 weeks after birth. Gestational age, foot and crown-heel lengths and birth weight were recorded. Radiographic measurements showed that the midshaft of the radius can be located with a positioning error of +/- 1.28 mm (+/- 2 S.E.E.) from the distance between the distal ulnar styloid process and proximal tip of the olecranon, both of which can be palpated in vivo. Scanning at 5 sites showed that effects of positioning errors on BMC measurements are least at the midshaft site. Subsequent measurements of the ash weight of sections of the radius and ulna, centred on the midshaft of the radius, showed that ash weight/unit length can be estimated with a standard error 2.99 mg/cm from scan data.

Prevention of intraventricular haemorrhage by fresh frozen plasma.

Seventy three preterm infants weighing less than 1500 g or less than 32 weeks' gestation, or both, were allocated randomly to treatment (fresh frozen plasma 10 ml/kg on admission and at 24 hours of age) or control groups. Fifteen (41%) out of 37 control patients sustained intraventricular haemorrhage compared with five (14%) of 36 patients receiving treatment (X2 = 5.24, P = 0.022). No difference was found in coagulation factors measured at birth or at 48 hours of age in both groups. Fresh frozen plasma appears to have a beneficial effect in the prevention of intraventricular haemorrhage.

Ophthalmic findings in very low birth weight children.

Recent advances in neonatal intensive care have led to a much improved survival rate in very low birth weight infants (under 1,500 g). A group of such children was examined and found to have a low incidence of serious visual or general handicap, but severe retrolental fibroplasia (RLF) affects a significant number.

Intravenous indomethacin for patent ductus arteriosus.

Intravenous indomethacin was given to 36 neonates with a patent ductus arteriosus who where receiving ventilatory support for respiratory distress syndrome. Permanent closure of the ductus arteriosus occurred in 21 (58%) infants and in this group the mean 24 hour plasma indomethacin concentration was 0.37 micrograms/ml. Partial success was achieved in 6 (17%) infants (mean 24 hour indomethacin concentration 0.34 micrograms/ml) but in 9 patients (mean 24 hour indomethacin concentration 0.29 micrograms/ml) there was no clinical change. Although the mean 24 hour indomethacin concentration was lower in the group with no clinical change, this was not statistically significant. Five of the 21 patients in whom there was permanent closure of the ductus required more than one dose of indomethacin. The possible effects of birthweight and age at indomethacin treatment were difficult to separate because of the high negative correlation between these two variables. The chance of closure was enhanced significantly if the patient had either a birthweight of at least 1 kg or the age at indomethacin treatment did not exceed 10 days, or both. Six hour but not 24 hour indomethacin concentrations were higher in patients with a high birthweight treated at an early age.

Effect of phototherapy on plasma 25(OH)-vitamin D in neonates.

The possibility that phototherapy may increase plasma levels of 25(OH)-vitamin D was assessed by measuring levels before and after 48 h continuous phototherapy using a standard phototherapy unit (Vickers, Basingstoke , England). There was no significant increase in plasma 25(OH)-vitamin D after 48 h phototherapy and it is concluded that such treatment does not stimulate photobiosynthesis of vitamin D.