Serum Albumin: How Useful as a Predictor of Operative Risk?
Consultations & Comments
Reader Reaction and Timely Answers From Experts
I enjoyed Dr Gregory Rutecki’s Top Papers of the Month column “The Ritual of Preoperative Consultation: Essential or Superfluous?” (CONSULTANT, June 2011, page 361), in which he mentioned that for low-risk procedures, such as cataract surgery, routine preoperative medical testing does not benefit patients or improve outcomes. About 2 months ago I went through a preoperative evaluation before I had cataract surgery. The operation took 5 to 6 minutes, and I was awake.
As for preoperative evaluation before more complicated surgery, I would like to call Dr Rutecki’s attention to a study that looked at preoperative serum albumin levels as a predictor of surgical risk.1 Included in the study were 54,215 major noncardiac non-emergent cases at 44 tertiary care Veterans Affairs (VA) medical centers. The investigators found that a decrease in serum albumin from concentrations greater than 4.6 g/L to less than 2.1 g/L was associated with an exponential increase in mortality rates from 1% to 29%, and in the morbidity rates from 10% to 65%. They concluded that serum albumin concentration is a better predictor of surgical outcomes than many other preoperative patient characteristics. It is a relatively low-cost test that should be used more frequently as a prognostic tool to detect malnutrition and risk of adverse surgical outcomes.
Albumin, the body’s predominant serum-binding protein, has several important functions:
•It comprises 75% to 80% of normal plasma colloid oncotic pressure and 50% of protein content. When plasma proteins, especially albumin, no longer sustain sufficient colloid osmotic pressure to counterbalance hydro-static pressure, edema develops.
•Albumin transports various substances, including bilirubin, fatty acids, magnesium, copper, zinc, uric acid, ions, vitamins, sex and thyroid hormones, and exogenous drugs.
•Alterations in the albumin level affect platelet formation.
•Optimal albumin levels indicate sound kidney and liver function and an unstressed immune system.
Synthesis occurs only in hepatic cells at a rate of about 15 g/d in a healthy person, but the rate can differ significantly with various conditions, including nephrotic syndrome, hepatic cirrhosis, heart failure, and malnutrition. Most cases of hypoalbuminemia are caused by acute and chronic inflammatory responses.
Serum albumin level is an important prognostic indicator. Among hospitalized patients, lower levels correlate with an increased risk of morbidity and mortality. At the time of hospital admission, 20% of patients have hypoalbuminemia.2
Richard Banfield, MD
New Canaan, Conn
References
1. Gibbs J, Cull W, Henderson W, et al. Preoperative serum albumin level as a predictor of operative mortality and morbidity: results from the National VA Surgical Risk Study. Arch Surg. 1999;134:36-42.
2. Peralta R. Hypoalbuminemia. Updated April 15, 2010. Medscape Updated Clinical Reference. http://emedicine.medscape.com/article/166724. Accessed August 18, 2011.
I partially agree, but also disagree. Albumin is a surrogate marker of overall “condition” and may be valuable before substantive surgery (elective abdominal surgery, for example). As a surrogate marker, how-ever, it is one of a plethora of signs that predict greater surgical risk. The VA study had an impact, but it was done in 1999. If a patient in the VA series had cirrhosis, it would be the liver disease per se (Child-Pugh-Turcotte score or Model for End-Stage Liver Disease [MELD] score) and not the albumin level (a secondary sign and not the primary disease) that better predicts surgical risk.1 Recent data assess perioperative risk in cirrhotic patients with Child-Pugh-Turcotte scores (a primary severity grading for liver disease), not with albumin levels.2
That said, I suspect that Dr Banfield and I would both agree that routine albumin measurements should not extend to cataract surgery risk predictions. Preoperative screening of any sort has not improved outcomes in this specific arena.
Albumin is one of many evaluations that help with assessment of surgical risk. They all should be incorporated into a holistic appraisal of risk. That said, additional workup and treatment (stress testing, bypass procedures, and prescribing beta-blockade) is where the problem may be located.
Gregory W. Rutecki, MD
Professor of Medicine
University of South Alabama College of Medicine
Mobile
References
1. Rutecki GW. What’s new in perioperative medicine? Consultant. 2009;49:778-779.
2. Eker HH, Ramshorst GH, de Goede B, et al. A prospective study on elective umbilical hernia repair in patients with liver cirrhosis and ascites. Surgery. 2011; [e pub ahead of print].