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Cysteine usage increases the need for acetate in neonates who receive total parenteral nutrition
L Laine1, R J Shulman, D Pitre
1Texas Children's Hospital, Houston.
Insights
Adding cysteine to total parenteral nutrition (TPN) solutions lowers infant serum carbon dioxide levels, increasing their need for acetate to prevent acidosis. This impacts neonatal acid-base balance during TPN.
Area of Science:
- Biochemistry
- Neonatal Medicine
- Pediatric Nutrition
Background:
- Total parenteral nutrition (TPN) is crucial for neonates unable to receive enteral feeding.
- Cysteine supplementation in TPN enhances mineral solubility but may affect acid-base balance.
- Neonatal acid-base homeostasis is delicate and susceptible to nutritional interventions.
Purpose of the Study:
- To investigate the impact of cysteine addition to TPN solutions on neonatal acid-base homeostasis.
- To determine if cysteine in TPN increases the requirement for acetate to manage potential acidosis.
- To assess the effect of cysteine on serum carbon dioxide levels in infants receiving TPN.
Main Methods:
- Comparative study of two neonate groups: one receiving TPN with cysteine (group C) and one without (group NC).
- In vitro analysis of TPN solution pH with and without cysteine hydrochloride.
- Monitoring of serum carbon dioxide levels and acetate intake during the first two weeks of TPN administration.
Main Results:
- In vitro, cysteine lowered TPN solution pH from 5.5 to 5.1.
- Infants in group C exhibited significantly lower serum carbon dioxide levels compared to group NC.
- Group C required significantly greater acetate intake, indicating a higher propensity for acidosis.
Conclusions:
- Cysteine addition to TPN solutions can induce or exacerbate metabolic acidosis in neonates.
- Monitoring acid-base balance and adjusting acetate supplementation is critical when using cysteine in neonatal TPN.
- Cysteine's effect on pH necessitates careful consideration in TPN formulation for vulnerable infant populations.
Abstract:
The addition of cysteine (as cysteine HCl) to a total parenteral nutrition (TPN) solution enhances calcium and phosphate solubility because cysteine lowers the pH of the solution. To determine whether adding cysteine to TPN solutions affected the acid-base homeostasis of infants and increased their need for acetate to obviate acidosis, we studied two groups of neonates--those receiving TPN before (group C) and after (group NC) the addition of cysteine. Measurements were made before and during the first 2 wk of TPN administration. We measured the pH of our standard TPN solution with and without the addition of cysteine. Serum carbon dioxide was significantly lower in group C despite a significantly greater intake of acetate in group NC. In the in vitro study the addition of cysteine to the TPN solution lowered the pH from 5.5 to 5.1. Newborns who received TPN solutions to which cysteine was added had lower serum carbon dioxide values and a greater need to receive acetate than did newborns who received TPN solutions without cysteine.