Zinc (Zn) and copper (Cu) are essential trace elements in people, being required for functional activity of several enzyme systems. In this study, we determined Cu and Zn concentrations in the serum of 105 healthy children randomly selected, aged 3-14 yr, residing in a region of Greece (Thrace), and we investigated their association with children's gender, age, height, weight, and nutritional habits. The mean levels of Zn and Cu were 15.01 +/- 2.95 micromol/L and 26.18 +/- 5.47 micromol/L, respectively, with no significant difference between boys and girls. Asignificant positive correlation was found between age and Zn levels, and a negative one was found between age and Cu levels. Both Zn and Cu levels tended to increase with height, whereas Zn levels significantly decreased with increasing body mass indent (BMI). The consumption of meat, milk, and eggs were independent determinants for higher Zn levels, and the consumption of legumes and fruits were independent determinants for higher Cu levels. Asignificant negative correlation was found between Zn and Cu levels. In conclusion, our study, the first one evaluating the serum status of Cu and Zn in healthy Greek children, identified significant correlations of Zn and Cu levels with their age, height, BMI, and nutritional habits.

Bone mineral status was assessed in 48 children with phenylketonuria (PKU) (20 M, 28 F, aged 2.5‐17 y). Bone density was measured in the distal third of the right forearm using single photon absorptiometry and was expressed as ±SD with respect to age‐ and gender‐matched controls. Serum calcium (Ca), magnesium (Mg), phosphorus (P), alkaline phosphatase (ALP), parathyroid hormone and 25‐hydroxyvitamin D were measured in morning samples. The ratios of urinary Ca/creatinine (UCa/ UCr), UP/UCr, UMg/UCr and hydroxyproline (OH‐Pr)/UCr were calculated in urine samples collected over a period of 3h. Patients' data were compared with those of 50 controls (22M, 28F, aged 3‐15y). The data showed severe osteopenia (below ‐2 SD) in 22/48 patients. Bone loss was more prominent in patients over 8y old. Bone density correlated significantly with age (r=– 0:56, p < 0.001) and with Phe (r=– 0:49, p < 0.007) but did not correlate with the other biochemical indices studied. Comparing PKU children with controls, significantly higher serum calcium and magnesium (p= 0:04, p< 0.001, respectively), lower ALP (p= 0:01), higher UCa/UCr ratio (p < 0.001), lower UP/UCr (p < 0.001) and lower UOH‐Pr/UCr (p < 0.001) were found. Dietary compliance was poor in patients over the age of 8y, as only 3/22 of ≤ 8y had mean serum phenylalanine >10mgdl−1, in contrast to 21/26 in the older group. It is clear from the data that osteopenia is commonly found in PKU patients from early life. The biochemical data indicate a metabolic state of low bone turnover in PKU patients. In conclusion, a better, more restricted diet may correct osteopenia.

SUMMARY Indices of renal excretion and reabsorption of phosphate were studied in 20 neonatal infants, 20 infants aged 3 months, and 20 infants aged 6 months. All subjects were normal and were fed a modified formula enriched with vitamin D. In neonatal infants all indices of phosphate excretion were found to be significantly lower and those of phosphate reabsorption significantly higher than in older infants. Phosphate excretion gradually increased with age, while its reabsorption decreased. The positive correlation between serum phosphorus and renal threshold phosphate concentration (TmP/GFR) and the negative correlation between phosphorus excretion index and TmP/GFR found in this study shows that in young infants as in adults TmP/GFR is the principal determinant of renal phosphate homeostasis. Among the many indices of renal phosphate handling in use TmP/GFR is the best for studies of phosphorus or calcium metabolism disorders, or both, especially in the first three months of life.The serum concentration of phosphate is much higher in neonates and infants than in older children or adults. The reason for this phenomenon remains obscure, although a relation between red cell 2,3 DPG, adenosine triphosphate, blood haemoglobin concentration, and serum phosphorus concentration has been previously reported. ' The mechanisms involved in maintaining a high serum phosphorus concentration in neonates and infants are numerous. The main food of this age is milk, which contains high quantities of freely absorbable phosphorus. Moreover, during the postneonatal period various hormonal and non-hormonal factors act on bones and kidneys, influencing the metabolism of phosphorus.Excretion of phosphate in the urine represents the final result of all these interactions and therefore can be used as an index of phosphate metabolism. Reports have been made on phosphorus excretion index2 in Bantu infants older than 4 months,3 urinary phosphate excretion in normal children older than one year,4 and renal threshold phosphate concentration (TmP/GFR) in children older than 6 years.5 These studies emphasised that proper interpretation of all indices of phosphorus excretion firstly required definition of age specific normal ranges, a condition that applies also for indices of phosphate reabsorption.6 The neonatal period and the first six months of life have their own specific metabolic characteristics, which for phosphate metabolism is primarily the high dietary intake of phosphorus. For this reason and also because of the unavailability of normal ranges for the renal handling of phosphate in this age group in the published reports we undertook the present study. Our results define the indices of urinary phosphate excretion and reabsorption in normal neonates and infants 3 and 6 months old. Subjects and methodsThree groups of subjects were studied. The first group consisted of 20 neonatal infants of both sexes aged 2-4 weeks. The second and third groups each consisted of 20 infants of both sexes and aged 3±0 5 and 6±0*5 months old, respective...