Renal failure protein requirement

Potassium is the second most abundant cation in the body and is found primarily in the intracellular fluid. Potassium has many important physiologic functions, including regulation of cell membrane electrical action potential (especially in the myocardium), muscular function, cellular metabolism, and glycogen and protein synthesis. Potassium in PN can be provided as chloride, acetate, and phosphate salts. One millimole of potassium phosphate provides 1.47 mEq of elemental potassium. Generally, the concentration of potassium in peripheral PN (PPN) admixtures should not exceed 80 mEq/L (80 mmol/L). While it is safer to also stick to the 80 mEq/L (80 mmol/L) limit for administration through a central vein, the maximum recommended potassium concentration for infusion via a central vein is 150 mEq/L (150 mmol/L).14 Patients with abnormal potassium losses (e.g., loop or thiazide diuretic therapy) may have higher requirements, and patients with renal failure may require potassium restriction. 

Modified amino acid solutions are designed for patients with altered protein requirements associated with hepatic encephalopathy, renal failure, and metabolic stress or trauma. However, these solutions are expensive and their role in disease-specific PN regimens is controversial. 

After a 1-g intravenous infusion, serum levels are 75-125 mcg/mL for most second-generation cephalosporins. Intramuscular administration is painful and should be avoided. Doses and dosing intervals vary depending on the specific agent (Table 43-2). There are marked differences in half-life, protein binding, and interval between doses. All are renally cleared and require dosage adjustment in renal failure. 

He was provided with a diet restricted in protein but was found to limit his own protein intake to 1.0 to 1.2 g/kg. Treatment with large doses of vitamin B12 for a period of 4 months made no difference to the concentration of methylmalonic acid excreted in his urine. He required frequent hospitalization for anorexia, vomiting, and dehydration. At 18 months of age he developed renal failure, and at 3 years he became oliguric. His physical development appeared normal for the first 12 months and then it deteriorated. He started to walk at 31 years, but at this time he also had hepatomegaly and persistent vomiting. On the basis of a developmental screening test he was found to be 12 to 18 months behind in all areas tested. 

Protein metabolism depends on both kidney and liver function therefore, protein requirements will be altered with decreased kidney or liver function (see Chap. 139). Critical illness (e.g., sepsis, burns, or trauma) will result in a hypercatabohc state in which there is increased protein synthesis and degradation. Consequently, protein requirements wiU be increased to 1.5 to 2 g/kg per day. In burn patients, protein requirements may be as high as 2.5 to 3 g/kg per day. Liver failure typically results in the need for protein restriction (0.5 g/kg per day) except if a hypercatabohc state is also present, in which case the requirement may be increased to 1.5 g/kg per day. Protein needs in renal failure are variable and affected by the various renal replacement therapies available. The apphcation of these guidelines requires both chnical judgment and frequent monitoring of renal and liver function, serum chemistries, chiucal condition, and nutrition outcomes (see Chap. 139). 

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