POSTNATAL CHANGES IN SOME RED CELL PARAMETERS

The red blood picture was studied in detail from birth to 12 weeks. The low point in the red cell count was reached in the seventh week, which represented the turning point from a negative to a positive balance between cell production and destruction. From the dynamics of the total number of circulating red cells it was concluded that, although erythropoiesis slows down after birth, a considerable amount of red cell production takes place during the first few postnatal weeks. The MCHC increased significantly over the first 5–6 postnatal weeks and remained constant thereafter. Macrocytes predominated at birth. Their percentage distribution decreased after the second week with a corresponding increase in microcytes. The red cell density distribution curve in the neonatal period is sigmoid in shape. The range of densities is, however, wider than in the adult. The curve shifts gradually to the heavy side from birth to 5 weeks, while from 5 to 12 weeks a shift back to the light side is observed. Macrocytes preponderate in the light fractions.     

POSTNATAL DEVELOPMENT OF RENAL FUNCTION IN PRE-TERM AND FULL-TERM INFANTS

ABSTRACT. Aperia, A., Broberger, B., Klinder, G., Herin, P. and Zetterström, R. (Department of Paediatrics, Karolinska Institute, St. Göran's Children's Hospital, Stockholm and Huddinge Hospital, Huddinge, Sweden). Postnatal deveopment of renal function in preterm and full-term infants. Acta Paediatr Scand, 70:183, 1981. –This study has been designed to examine the effect of gestational age (GA) on the postnatal development of renal function and has been performed in pre-term (PT) infants (GA=30–34 weeks) and in full-term (FT) infants (GA=39–41 weeks). Postnatal age has ranged from 1–35 days. From 8 hour urine samples collected after spontaneous voiding and a capillary blood sample, determinations have been made of the clearance of creatinine (C_Cr), the fractional excretion of β₂-microglobulin (FE_β2) and the fractional excretion of sodium (FE_Na). In some infants receiving fluid parenterally, simultaneous determinations were made of the clearance of creatinine and inulin. As judged from this study, C_Cr is a reliable indicator of the glomerular filtration rate (GFR). GFR was almost the same in newborn PT and FT, but from 0.3–1 week of age GFR increased significantly more rapidly in FT than in PT. From 1–5 weeks of age GFR increased at approximately the same rate in PT and FT infants. The absolute value for GFR in 3–5 weeks old infants was lower in PT than in FT. FE_β2 was higher in PT than in FT infants during the entire first month of life and FE_Na was higher in PT than in FT infants during the first week of life, suggesting a glomerular tubular imbalance at least at the level of the proximal tubule in PT infants. It is concluded that different stages of maturation will alter the preconditions for the renal adaptation to extrauterine life during at least the first month of life. Therefore special attention must be paid to the limited renal function in PT during their entire first month of life.     

POSTNATAL CHANGES IN THE ABILITY OF PLASMA ALBUMIN TO BIND BILIRUBIN

ABSTRACT. The plasma concentrations of total albumin, unconjugated bilirubin and reserve albumin for bilirubin binding were determined in 407 healthy infants of various age up to eight days. The albumin reserve was measured using monoacetyldiaminodiphenyl-sulfone (MADDS) as a deputy ligand for bilirubin. The fraction of albumin capable of binding bilirubin was calculated as the sum of the concentrations of bilirubin and reserve albumin, divided by the total albumin concentration. Our data showed that this fraction was low (average 0.36) and did not change during the first 24 hours of life, and in this period it was independent of the maturity of the infant, as expressed by its birth weight or gestational age. From about 24 hours of life, the fraction began to increase. This increase came to an end about 60 hours after birth, and no further changes were seen during the following five days. The level of the bilirubin-binding fraction reached 60 hours after birth was related to the maturity of the infant: It increased with increasing birth weight up to 3000 g and with increasing gestational age up to 275 days, when on an average it was about 0.58. The fraction of binding albumin was independent of the sex.     

EARLY POSTNATAL GROWTH OF LOW BIRTHWEIGHT INFANTS: WHAT IS OPTIMAL?

Stern, L. (Department of Paediatrics, Brown University, R.I., USA). Early postnatal growth of low birthweight infants: what is optimal? Acta Paediatr Scand, Suppl. 296: 6, 1982. — The question as to what is optimal depends on an examination of a number of questions which may be stated as follows: 1) Does physical growth as expressed by height and weight bear any relationship to functional or intellectual development? 2) Should postnatal growth of low birthweight (preterm) infants proceed at their presumed in utero growth rate? 3) Does caloric intake beyond a minimum level influence the growth rate and intellectual development of SGA infants? 4) What is optimal—or do we all need to be the same? These questions imply a projected benefit to nutritional techniques, amounts, and procedures. Against these must be balanced potential hazards which relate to a number of specific factors. These include the effort and expenditure of energies involved in feeding practices. The hazards inherent in gavage, intraluminal, and other forms of forced nutrition. Solute loading and the relationship of solute to free water content. The ommission of specific nutrients from any dietary regimen and the toxicity of other specific contents. A balanced approach combining all of these may best decide what is "optimal".     

POSTNATAL CONTROL OF WATER AND ELECTROLYTE HOMEOSTASIS IN PRE-TERM AND FULL-TERM INFANTS

Aperia, A., Broberger, O., Herin, P., Thodenius, K. and Zetterström, R. (Department of Paediatrics, Karolinska Institute, St. Göran's Children's Hospital, Stockholm, Sweden). Postnatal control of water and electrolyte homeostasis in pre-term and full-term infants. Acta Paediatr Scand, Suppl. 305: 61–65, 1983.—A review is given of the progress which has been made during the last decade within the field of renal control of water and sodium homeostasis in newborn infants of varying gestational age. Both preterm and full-term infants have a low capacity for rapid excretion of a salt load. The natriuretic response improves gradually up to the age of 15 months. The capacity to excrete a load of sodium bicarbonate is higher than to excrete a load of sodium chloride. Under basal conditions preterm infants of a gestational age below 35 weeks have a higher renal sodium excretion than full-term infants. They also appear to be unable to retain sodium when in negative balance. The capacity to concentrate the urine is low in newborn infants, the maximal osmolality being only slightly above that of plasma. The concentrating capacity increases relatively fast during the first 4–6 postnatal weeks in full-term as well as in pre-term infants but does not reach the adult level until the second year. Water loaded newborn infants are able to excrete a urine with a osmolality as low as 30–50 mOsm per kg. In full-term infants free water clearance per unit filtered water is higher than in adults. Water-loaded pre-term infants with a gestational age of more than 30 weeks also have a supernormal diluting capacity.     

POSTNATAL DEVELOPMENT OF RENAL HYDROGEN ION EXCRETION CAPACITY IN RELATION TO AGE AND PROTEIN INTAKE

ABSTRACT. Svenningsen, N. W. and Lindquist, B. (Department of Paediatrics, University Hospital, Lund, Sweden). Postnatal development of renal hydrogen ion excretion capacity in relation to age and protein intake. Acta Paediatr Scand, 63: 721, 1974.—The cumulative and maximum renal hydrogen ion excretion capacity after induced acidosis has been studied in six term and twenty preterm infants at 1–3 and 44 weeks of postnatal age corresponding to for preterm babies 34–36 and 37–39 and for term babies 41–43 and 44–46 weeks of gestational age. The maximum net hydrogen ion (H⁺_NAE) excretion capacity is lower in preterm than in term infants at 1–3 weeks of postnatal life. However, when approaching full gestation there is a considerable increase of the H+_NAE excretion capacity of pretem infants almost equal to that found in term infants at 1–3 weeks of age. High dietary protein intake lasting for in average two to three weeks in preterm infants does not change the maximum renal H⁺ excretion during induced acidosis, but significantly enhances the initial increment of excretion rate of titratable acid (H⁺_TA) in comparison to preterm infants fed low protein diets. The findings of the present investigation suggest that the development of renal hydrogen ion excretion capacity in preterm infants during the first weeks of life is related primarily to gestational age. This development may, however, to a certain degree respond to increased excretory needs imposed by dietary load.     

INTERNATIONAL COMPARISONS OF POSTNATAL GROWTH OF LOW BIRTHWEIGHT INFANTS WITH SPECIAL REFERENCE TO DIFFERENCES BETWEEN DEVELOPING AND AFFLUENT COUNTRIES

Hofvander Y. (International Child Health Unit, Department of Paediatrics, University of Uppsala, Sweden). International comparisons of postnatal growth of low birth-weight infants with special reference to differences between developing and affluent countries. Acta Paediatr Scand, Suppl. 296:14, 1982. A large majority of low birthweight infants are born in developing countries where however, only few follow-up studies have been made. However, there are clear indications that in general the AGA infants catch-up better than the SGA of the same weight. A particularly poor catch-up growth is shown by full-term SGA indicating that if a fetal growth retardations is diagnosed, delivery should be induced prematurely. Social and environmental factors are important for the optimal growth postnatally and particularly so if the environmental conditions are adverse.     

THE EFFECTIVENESS OF PHENOBARBITAL IN THE PREVENTION OF RECURRENT FEBRILE CONVULSIONS IN CHILDREN WITH AND WITHOUT A HISTORY OF PRE-, PERI- AND POSTNATAL ABNORMALITIES

Abstract. Three hundred children who had an initial febrile convulsion were divided into two groups. In one group were children with a single brief generalized initial febrile seizure and no history of pre-, peri- or postnatal abnormalities which might suggest the possibility of brain damage and in the other group those with such abnormalities and/or a "severe" initial febrile convulsion. Daily phenobarbital produced a significant decrease in febrile seizure recurrences in both groups, as compared to children who received phenobarbital at the onset of fever and no phenobarbital prophylaxis. "Intermittent" phenobarbital given at the onset of fever did not produce a significant difference in recurrence rate as compared with no phenobarbital.