What are normal laboratory values and how are they interpreted in the patient with chronic kidney disease?

Review of the laboratory reports is included in the overall patient assessment. Any deviations from normal should be further evaluated for what is an acceptable value for a dialysis patient. For example, creatinine and BUN values may not fall within the range of normal because of chronic kidney disease (CKD). However, dialysis personnel should follow a protocol that defines when the BUN and creatinine values exceed the acceptable range for a person on dialysis and take appropriate action. Deviations from the acceptable range of laboratory values should be reported to the dialysis physician for appropriate intervention. Interventions may include a change in the dialysis prescription and/or medication.

What is albumin?

Albumin is a form of protein, which is a good measure of the nutritional status of an individual. It is also the protein of highest concentration in the plasma. Albumin carries smaller molecules in the blood, such as medications, bilirubin, and calcium. Albumin helps to hold fluid in the blood vessels and is a good reflection of the patient’s protein stores. It is well known that albumin is a powerful predictor of morbidity and mortality in the CKD patient. The normal value ranges from 3.5 to 5.4 g/dL. A serum albumin of 4.0 g/dL or greater is desired for the CKD patient.

What are the symptoms of low albumin?

Low albumin will cause edema as fluid shifts from the blood vessels into the tissues. Other symptoms of hypoalbuminemia include weight loss, fatigue, muscle wasting, and hypotension.

Why are dialysis patients at risk for low albumin levels?

Albumin levels are greatly influenced by diet. Dialysis patients are well known for having poor nutrition because uremia causes a loss of appetite. Lack of knowledge regarding adequate protein intake, difficulties with cooking or shopping for food, nausea, and loss of appetite for protein-rich food are all barriers supporting good nutrition in the dialysis patient. Some patients lose albumin into the urine, and peritoneal dialysis patients are at a high risk of lowering their levels as albumin is transported across the peritoneal membrane.

Why do we monitor albumin levels so closely?

A low albumin level (hypoalbuminemia) is linked to higher hospitalization rates and is one of the greatest predictors of death in the dialysis patient. In most studies, the risk for morbidity and mortality increases with a serum albumin level less than 3.5 g/dL (Ahmad, 1999).

What is the relationship between albumin levels and c-reactive protein?

C-reactive protein (CRP) is a protein produced in response to infection, inflammation, and tissue trauma and is used as a marker for inflammation. An elevated level of serum CRP is associated with a low serum albumin level in dialysis patients. A combination of the two factors has been identified as placing the dialysis patient at a higher risk for developing heart disease and inflammation of the blood vessels. CRP is present in the serum of normal individuals at levels between 0 and 5 mg/L. Serum CRP levels increase dramatically during infection or injury. Other factors associated with an increase in CRP levels in the CKD patient include surgery, bioincompatible membranes, periodontal disease, high-flux dialysis, impure dialysate, arthritis, and uremia. Levels may increase 100 times or more during bacterial or viral infection. The CRP level will peak two to three days after an acute infection and begin to decrease one to two weeks after the infection subsides. This is why CRP is useful as an early marker for infection, inflammation, or injury. CRP measurements may help predict low serum albumin levels, evaluate for resistance to epoetin alfa (Epogen) therapy, assess the course of acute bacterial infections and their response to treatment, and detect occult infections or chronic inflammation (Spectra Renal Management, 2009). The National Kidney Foundation (NKF) Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines suggest a CRP level greater than 5 to 10 mg/L as being indicative of inflammation (NKF, 2006).

Are dialysis patients at risk for aluminum toxicity?

Aluminum is a light metal found in cookware, soft drink and other beverage cans, antacids, cosmetics, antiperspirants, aluminum-containing phosphate binders, and contaminated water. The kidneys are the main organs for the filtration and excretion of aluminum in the body. The majority of aluminum is protein bound so it is not easily diffused through the glomerulus. Deposition of aluminum in the bone, tissues, and brain will be seen with elevated levels.

Aluminum toxicity was once prevalent among dialysis patients because they were exposed to aluminum from the water used in the dialysis treatment and from the oral intake of aluminum-based binders. The use of aluminum-based phosphate binders is now generally avoided due to the harmful effects of aluminum accumulation in the patient. The clinical consequences of aluminum toxicity involve symptoms to the brain, bone, and blood. These may or may not occur concurrently. High serum aluminum levels are associated with progressive neurologic symptoms, such as behavioral changes, slurred speech, and memory loss, that occur very subtly over time. Gastrointestinal (GI) irritation, loss of energy and appetite, anemia, and constipation also are associated with elevated aluminum levels. Dementia may be seen with advanced toxicity. Elevated aluminum levels may also cause epoetin alfa–resistant anemia and aluminum-induced bone disease. Normal serum levels are 0 to 10 mcg/L.

What is the treatment for aluminum toxicity?

Aside from removing the sources of exposure, the chelating agent deferoxamine mesylate (Desferal) may be used to remove the excess aluminum. To chelate means to remove a heavy metal, such as lead, mercury, or aluminum, from the bloodstream. When administered, deferoxamine mesylate will form complexes with the aluminum, which can then be removed from the blood during the dialysis treatment.

How does potassium work inside the body?

Potassium is the major intracellular cation and the second most abundant cation in the body. All but 2% of the total body potassium is within the cells of the body. Potassium is necessary for many cellular functions; neuromuscular control; skeletal, cardiac, and smooth muscle activity; and intracellular enzyme reactions. Potassium is influenced by acid-base balance as potassium ions are shifted out of the cell and replaced with hydrogen ions with acidosis. The majority of excess potassium in the body is excreted by the kidneys in the urine.