Leptin a new biological marker for evaluating malnutrition in elderly patients

There is no single universally accepted biochemical marker of nutritional status in the elderly. Many markers are affected by non-nutritional factors.

The purpose of this study was to determine the biological parameters best related to anthropometric markers of malnutrition in an elderly polypathological population, and determine cutoff values for these potential parameters to diagnose malnutrition.

This prospective study enrolled 116 elderly hospitalized patients and 76 elderly outpatients. Nutritional status (albumin, transthyretin, body mass index (BMI), skinfold thickness) and biological parameters (leptin, insulin-like growth factor-1 (IGF-1), IGF binding protein-1 (IGFBP-1), IGFBP-3, C-reactive protein (CRP), orosomucoid) were assessed. We defined malnutrition according to the lowest quartile of BMI and skinfold thickness measured in a large healthy elderly French sample population.

In this sample of elderly patients (age: 85+/-7 years old), leptin concentration was the only biological parameter significantly related to nutrition status. Independent correlations were found between leptin concentration and BMI, skinfold thickness and sex. The relationship between nutritional status and leptin concentration is significantly different in each sex: the more the patients are undernourished, the lower the leptin concentration in both sexes. The optimal leptin cutoff value for the diagnosis of malnutrition in this population was 4 microg/l in men (sensitivity 0.89, specificity 0.82) and 6.48 microg/l in women (sensitivity 0.90, specificity 0.83).

Leptin concentration is highly correlated with anthropometric data whereas albumin or transthyretin are known to be also influenced by morbidity and inflammatory conditions. Serum leptin concentration could be used for nutritional assessment in elderly patients with acute diseases.