Potassium metabolism in extremely low birth weight infants in the first week of life

doi:10.1016/S0022-3476(97)70128-8

The Journal of Pediatrics

Volume 131, Issue 1, July 1997, Pages 81-86

https://doi.org/10.1016/S0022-3476(97)70128-8 Get rights and content

Abstract

Objective: Nonoliguric hyperkalemia has been reported to occur in the first week of life in as many as 50% of extremely low birth weight (ELBW) infants. We studied potassium balance and renal function in the first 5 days of life to characterize potassium metabolism during the three phases of fluid and electrolyte homeostasis that we have described in ELBW infants and to elucidate the factors that contribute to the development of nonoliguric hyperkalemia.

Study design: Plasma potassium concentration (PK), potassium intake and output, and renal clearances were obtained for the first 5 days of life in 31 infants with a birth weight of 1000 gm or less. Collection periods in which urine flow rate was greater than or equal to 3 ml/kg per hour and weight loss was greater than or equal to 0.8 gm/kg per hour were denoted to be diuretic. Prediuresis includes all collection periods before the first diuretic period; diuresis includes all collection periods between the first and last diuretic periods; postdiuresis includes all collection periods after the last diuretic period. Infants with a PK greater than 6.7 mmol/L on at least one measurement were denoted to have hyperkalemia.

Results: PK increased initially after birth—despite the absence of potassium intake—and then decreased and stabilized by the fourth day of life. Diuresis occurred in 27 of 31 infants. The age at which PK peaked was closely related to the onset of diuresis. PK decreased significantly during diuresis as the result of a more negative potassium balance, despite a significant increase in potassium intake. In fact, PK fell to less than 4 mmol/L in 13 of 27 infants during diuresis. After the cessation of diuresis, potassium excretion decreased even though there was a significant increase in potassium intake, potassium balance was zero, and PK stabilized. Hyperkalemia developed in 11 of 31 infants. The pattern of change in PK with age was similar in infants with normokalemia and hyperkalemia: PK initially increased (essentially in the absence of potassium intake) and then decreased and stabilized by the fourth day of life. However, the rise in PK after birth was greater in infants with hyperkalemia than in those with normokalemia: 0.7 ± 0.2 versus 1.8 ± 0.2 mmol/L ( p < 0.001). No differences in fluid and electrolyte homeostasis or renal function were identified as associated with hyperkalemia.

Conclusions: PK increases in most ELBW infants in the first few days after birth as a result of a shift of potassium from the intracellular to the extracellular compartment. The increase in the glomerular filtration rate and in the fractional excretion of sodium, with the onset of diuresis, facilitates potassium excretion, and PK almost invariably decreases. Hyperkalemia seems to be principally the result of a greater intracellular to extracellular potassium shift immediately after birth in some ELBW infants. (J Pediatr 1997;131:81-6)

Section snippets

Methods

The study protocol was approved by the institutional review board of the State University of New York at Stony Brook. Infants with appropriate size for gestational age and birth weight of 1000 gm or less were enrolled in the study as soon after birth as informed parental consent could be obtained. Infants with congenital heart disease, renal failure, or major congenital anomalies and infants more than 24 hours of age or who had received more than 20 ml/kg of blood products before enrollment

Results

Thirty-two infants appropriate in size for gestational age, with birth weight of 1000 gm or less, were enrolled in the study. After enrollment, one infant had acute renal failure with hyperkalemia and was excluded from these results. Birth weights of the remaining 31 infants ranged from 539 to 1000 gm, with a mean (±SD) of 818 ± 128 gm. Gestational age ranged from 23 to 30 weeks, with a mean (±SD) of 26 ± 1 weeks.

Mean PKs are depicted as a function of age for the entire group in Fig. 1 .

. Mean

Discussion

Our findings characterized the first 1 to 3 days of life in ELBW infants as a period of unique vulnerability to hyperkalemia, even in the absence of factors otherwise known to predispose infants to this life-threatening electrolyte imbalance. This is the result of at least two phenomena. The first is a shift of potassium from the intracellular to the extracellular space. The increase in PK observed in the first day of life in most of our subjects, in the absence of exogenous potassium

References (17)

SG Shaffer et al.
Hyperkalemia in very low birth weight infants
J Pediatr
(1992)
JL Stefano et al.
Decreased erythrocyte Na + ,K + -ATPase activity associated with cellular potassium loss in extremely low birth weight infants with nonoliguric hyperkalemia
J Pediatr
(1993)
JL Stefano et al.
Nitrogen balance in extremely low birth weight infants with nonoliguric hyperkalemia
J Pediatr
(1993)
K Sato et al.
Internal potassium shift in premature infants: cause of nonoliguric hyperkalemia
J Pediatr
(1995)
DA Lee et al.
Reducing blood donor exposures in low birth weight infants by the use of older, unwashed packed red blood cells
J Pediatr
(1995)
R. Usher
The respiratory distress syndrome of prematurity. I. Changes in potassium in the serum and the electrocardiogram and effects of therapy
Pediatrics
(1959)
I Gruskay et al.
Nonoliguric hyperkalemia in infants weighing less than 1000 grams
J Pediatr
(1988)
Y Fukuda et al.
Factors causing hyperkalemia in premature infants
Am J Perinat
(1989)

There are more references available in the full text version of this article.

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Potassium metabolism in extremely low birth weight infants in the first week of life☆,☆☆

Abstract

Section snippets

Methods

Results

Discussion

J Pediatr

J Pediatr

J Pediatr

J Pediatr

J Pediatr

The respiratory distress syndrome of prematurity. I. Changes in potassium in the serum and the electrocardiogram and effects of therapy

Pediatrics

Nonoliguric hyperkalemia in infants weighing less than 1000 grams

J Pediatr

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Am J Perinat