Late hyponatremia in premature infants: Role of aldosterone and arginine vasopressin

Influence of NaCl Supplementation on Vasopressin Secretion and Water Excretion in Premature Infants

“…This approach assumes that hyponatremia is mainly the re-suit of high volume intake induced natriuresis and water retention [ 13,14]. The possible role of excess AVP and free water retention has also been claimed because during the course of late hyponatremia there has been a progres sive increase in daily AVP excretion [4]. Ex tracellular volume contraction due to primary sodium deficiency and decreased intravascu lar volume in association with hypoalbuminemia have been proposed as a stimulus for AVP release [4][5][6], In this regard, it is to be considered that although total body water and extracellular water estimates by Roy et al [3] indicate no difference in very low birth weight infants with or without hyponatremia, Shaffer et al [15] have demonstrated that infants de veloping late hyponatremia have significantly lower extracellular volume han infants who maintain normal serum sodium concentra tions.…”

“…In a previous study we have demonstrated simul taneous increase in urinary aldosterone and AVP excretion in association with progressive hyponatremia in a group of healthy prema ture infants. Protracted renal sodium loss has been claimed, therefore, to result in extracel lular volume contraction, stimulation of AVP secretion, enhancement of renal water reab sorption, and as a consequence in a fall in plasma sodium concentration [4], This con tention, however, has been challenged be cause hypoalbuminemia, frequently encoun tered in low birth weight neonates, has also been shown to produce hyponatremia through a reduction of the circulatory volume which may act as a stimulus for AVP excretion [5,6]. It is of further concern that in our study the urinary AVP excretion was not corrected for creatinine or glomerular filtration rate, thus its increasing daily excretion rate with age might reflect improving renal function rather than an increase in pituitary AVP secretion.…”

Serum calcium and magnesium in diabetes control

“…Transient endocrine disorders, such as diabetes insipidus, adrenal insufficiency or hypothyroidism, which have been associated with false-positive sweat tests, were ruled out in our patient [5]. Only the normalization of the morning blood cortisol level could be related retrospectively with normalized results of the sweat test in our patient.…”

“…Only the normalization of the morning blood cortisol level could be related retrospectively with normalized results of the sweat test in our patient. Sweat was collected by pilocarpine iontophoresis and quantitative measurements of Na +, C1-and K + were performed, following the procedure of Shwachman et al [5]. A reduced level of cellular glucocorticoid receptors in mononuclear leucocytes has been demonstrated in some anorexia nervosa patients [3].…”

Endogenous digoxin-like substance in the urine of preterm infants with late hyponatremia

“…Since preterm delivery is thought to be associated with relative hypervolemia in the newborn, these observations suggest that, due to its natriuretic properties, EDLS may contribute to a complex situation of postnatal development. Thus, EDLS, which cross-reacts with immunoassay antibodies to digoxin, might reflect the activity of a fourth major humoral volume regulatory system, acting with renin-angiotensin-aldosterone, the vasopressin and atrial natriuretic factor systems [5,6]. …”