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The lab's role in nutritional assessment of patients.

The lab's role in nutritional assessment of patients

This lab's prealbumin testing detects malnourished patients, while other tests help clinicians manage these cases to avoid excess length of stay. By Larry H. Bernstein, M.D.

A simple, accurate marker for protein and calorie malnutrition promises to save more than one-half million dollars per year at our 537-bed hospital.

The test, measuring prealbumin, alerts clinicians at an early stage to the threat of nutrition-related complications that could extend a patient's length of stay. Thereafter, a nutrition support team at the hospital helps the medical staff treat malnutrition and monitors the effectiveness of such therapy.

Malnutrition in hospitalized patients is well documented and occurs commonly as a result of stress of injury or of major surgery. It also is present in defined clinical states, such as inability to use the gastrointestinal tract for more than a week after surgery, major disorders of the GI tract reducing calorie and protein intake, burns over more than 30 per cent of the body's surface, cerebrovascular accident, and ventilator dependence, to name a few.

Six thousand adult patients a year fall into these categories at our hospital. We have begun performing prealbumin testing on all of them, starting at admission. Nurses initially identify them as being at risk of nutrition-related complications, on the basis of the protocol in Figure I. The nurses then alert dietitians and clinicians.

Failure to detect and correct malnutrition results in costly further deterioration of nutrient status. This can lead to such complications as impaired healing of wounds, would dehiscence, immunodeficiency, a greater possibility of opportunistic and other infections, failure of treatment, and with these, delayed discharges and increased mortality.

The presence of protein-calorie malnutrition in hospitalized patients, defined by a serum albumin of less than 3.5 g/dl and a total lymphocyte count of less than 1,500/mm3, is associated with a fourfold increase in severity of illness and a sixfold increase in mortality. Moreover, a serum albumin of less than 2 g/dl is associated with a high mortality rate: 60 per cent in 30 days among patients at risk of nutrition-related complications.(1)

(1) Reinhardt, G.S.; Nyscoski, J.W.; Wilkins, D.B.; et al. Incidence and mortality of hypoalbuminemic hospitalized patients. J. Parenter. Enter. Nutr. 4:357-359, 1980.

A recent study supported by Ross Laboratories has demonstrated that hospital malnutrition extends length of stay by three to five days and results in excess charges of $1,500 to $2,500 per hospital stay.(2) The study suggests that the annual cost of failing to diagnose hospital malnutrition in the U.S. could be $2.5 billion.

(2) Hull, S. The cost of malnutrition. Presented at the Bridgeport Hospital Symposium; Product Line Management of the Laboratory Under DRGs, Feb. 13, 1986, Windsor Locks, Conn.

There has been an intense debate in the literature about the relative merits of two different approaches for identifying patients at risk of nutrition-related complications -- subjective global assessment (a detailed nutritional history combined with weight and other physical measurements) versus widely used serum albumin and transferrin measurements. In my view, the two approaches are equally good but not good enough.

Albumin, the most important transport protein in serum, has a half-life of 21 days and responds slowly to changes in therapy. While it may be an excellent determinant for identifying the severely ill patient, it is considered an insensitive marker for protein-calorie malnutrition.(3)

(3) Forse, R.A., and Shizgal, H.M. Serum albumin and nutritional status. J. Parenter. Enter. Nutr. 4: 450 -- 454, 1980.

The poor sensitivity of serum albumin for identifying early protein-calorie malnutrition led to the additional use of transferrin measurement. Transferrin, the transport protein for iron, has a a half-life of eight days and is not affected by changes in water balance. It is commonly calculated by linear regression from the measurement of total iron binding capacity, the transferrin being about 0.8 times the TIBC. There is poor correlation between the transferrin from TIBC and the transferrin measured by immunoassay, however. The correlation between transferrin and albumin is also inadequate.

Variation in transferrin may make it unacceptable as a nutritional marker.(4) And recently, albumin, transferrin, and the weight/height index were shown to be inadequate for predicting outcome in healthy and hospitalized groups.(5)

(4) Roza, A.M.; Tuitt, D.; and Shizgal, H.M. Transferrin -- A poor measure of nutritional status. J. Parenter. Enter. Nutr. 8: 523-528, 1984.

(5) Prabhakaran, V.M.; Pujara, S.; Mills, A.J.; and Whalen, V.W. Can nutritional criteria help predict outcome in hospitalized patients? Clin. Chem. 32: 2077 -- 2079, 1986.

Because of the insensitivity of albumin and transferrin, other proteins have drawn interest as means of assessing protein-calorie malnutrition and monitoring therapy -- particularly proteins with half-lives within 48 hours.

Prealbumin, a major transport protein, has a half-life of 1.9 days. Its normal range in serum is 16 to 40 mg/dl on our nephelometric protein analyzer, and it increases with restoration of nutritional status at a daily rate of more than 1 mg/dl. A concentration between 10.7 and 16 mg/dl indicates moderate protein-calorie malnutrition and patients who are likely to benefit from early nutritional support. Below 10.7 mg/dl, patients are usually seriously malnourished.

These are fairly reliable parameters. They make prealbumin superior in sensitivity to both albumin-transferrin testing and subjective global assessment.

Three major goals are required in a nutritional program, and the laboratory should be central to all of them. First, as we have discussed, is the need to identify patients at risk of nutrition-related complications. Second is a need to develop a nutritional plan based on estimated nutrient requirements. Third is a need to monitor for the attainment of nutritional goals.

Although developing a treatment plan and monitoring its progress are quite dependent on the laboratory, labs are inconspicuous in the nutritional programs of many hospitals. That is not the case at our institution.

We have developed a multidisciplinary team approach to solving nutritional problems. This came about gradually, starting with formation of a nutrition committee in 1972 by Walter Pleban, M.D., a surgeon who realized the importance of Dr. Stanley Dudrick's success in total parenteral feeding of puppies at the University of Pennsylvania.

Dr. Pleban was joined by clinical dietitian Marion Feitelson, who eventually became department chairperson in nutrition services before moving to a major university. Feitelson and her successor at our hospital, Carla Leukhardt, established the standards for an audit that helps insure adequate nutritional care of patients.

In 1986, activities of the nutrition committee were expanded through creation of a nutrition support team. Under the direct supervision of Dr. Pleban as chairman of the nutrition committee, the support team was charged with development of policies and procedures for total parenteral nutrition and continuing surveillance of nutritional practices.

A pathologist (the author) was chosen as medical coordinator of the team. Other members include two dietitians, one with the team full time in intensive care units; a pharmacist who spends half his time on the team, checking for interactions between therapeutic drugs and the nutritional products received by the malnourished patient, as well as making recommendations about administration of those products; and a nurse assigned to the team for two hours a day, seeing that the products are delivered to the patient properly and that catheter care is adequate. These members represent others in their respective departments who also become involved in nutritional support activities.

Assessment and monitoring of patients by dietitians and pharmacists are extremely dependent upon the laboratory, not only for albumin and prealbumin but also for urinary nitrogen and creatinine, and for serum electrolytes, glucose, triglycerides, and other analytes.

The dietitians evaluate all hospital patients on the basis of diagnostic criteria (e.g., Crohn's disease), functional criteria (e.g., no oral intake for seven days), and empirical criteria (e.g., weight loss and anthropometric measurements). Further evaluation may be considered, depending upon the severity of illness and the attending physician's expressed interest. Once a patient is identified as in need of special nutritional support, the physician has 72 hours to respond and pursue a treatment plan.

The plan is usually worked out in consultation with the nutrition support team. Initially, I was kept very busy consulting because physicians did not feel the dietitians knew the clinical situation. Now most physicians accept recommendations from the dietitians, although the latter still refer some cases to me. As a hospital-based physician, I do not receive consulting fees and am not regarded as a competitor by members of the medical staff.

Through the nutrition committee, our hospital has held a number of workshops for physicians on nutritional assessment and treatment in recent years. All of our efforts may appear to be excessive at a time when hospitals are dealing with prospective payment and staffing is critical. Consider, however, that the cost of nutritional support is moderate -- while the unanticipated cost of nutrition-related complications may run into billions of dollars nationwide.

Protocol for identifying patients at risk of nutrition-related complications

The nutrition committee has recommended a set of indications to initiate use of an approved nutrition assessment order form (which is to be placed in the medical record for the signature of the attending physician) or to initiate an assessment by the physician or house staff.

The indications for assessment are:

1. Reddening at pressure point -- focus for decubitis ulcer or actual ulcer.

2. No oral intake except for clear liquids, or poor oral intake for more than five days.

3. No oral intake with only peripheral parenteral nutritional support for more than seven days.

4. Major trauma or major surgery with expected decline in nutritional status.

5. Specific diagnosis and/or preadmission condition associated with chronic nutrient depletion, such as respiratory failure.

6. Unintentional weight loss of more than 10 per cent in six months or more than 5 per cent in one month (percentage weight loss = weight loss divided by usual body weight). Complaints of 10 to 15 lbs. weight loss over one to two months.

7. Admission weight less than 80 per cent of usual body weight (current weight divided by usual body weight).

8. Need to improve nutritional status prior to discharge and/or need for outpatient nutritional follow-up to improve or maintain nutritional status after discharge.

9. Complications arising secondary to medical or surgical therapy that prolong the patient's inability to ingest or digest food and absorb nutrients, or that alter metabolism and/or nutrient requirements.

If the suggested indications point to a need for assessment and are observed by a dietitian or nurse looking after the patient, the attending physician will be notified and the need for assessment will be noted with a reference to the protocol for use of a nutrition assessment order form. If the physician does not respond to the documentation of need for assessment in 72 hours, the problem will be called to the attention of the medical coordinator of the nutrition support team.
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Article Details
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Author:Bernstein, Larry H.
Publication:Medical Laboratory Observer
Date:Apr 1, 1988
Previous Article:Hearings begin on need for increased lab regulation.
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