Background: Involuntary weight loss frequently poses a diagnostic challenge. Patient and physician alike want to exclude malignant and other major organic illness. The present study aimed to evaluate whether a negative baseline evaluation (consisting of clinical examination, standard laboratory examination, chest X-ray, and abdominal ultrasound) lowers the probability of evolving organic illness in patients with significant unexplained weight loss.
Methods: Prospective observational study of 101 consecutive patients presenting to a general internal medicine department of a university hospital with an unexplained unintentional weight loss of at least 5% within 6-12 months. Laboratory tests of interest included C-reactive protein, albumin, haemoglobin, and liver function tests.
Results: Weight loss of the 101 patients [age (mean, interquartile range): 64 (51-71) years, 46% male] averaged 10 (7-15) kg. Organic causes were found in 57 patients (56%), including malignancy in 22 (22%). In 44 patients without obvious organic cause for the weight loss (44%), a psychiatric disorder was implicated in 16 (16%) and no cause was established in 28 (28%), despite vigorous effort and follow-up of at least 6 months. Baseline evaluation was entirely normal in none of the 22 patients (0%) with malignancy, in 2 of the 35 (5.7%) with non-malignant organic disease, and in 23 of the 44 (52%) without physical diagnosis. Additional testing, oftentimes extensive, after a normal baseline evaluation led to one additional physical diagnosis (lactose intolerance).
Conclusion: In patients presenting with substantial unintentional weight loss, major organic and especially malignant diseases seem highly unlikely when a baseline evaluation is completely normal. In this setting, a watchful waiting approach may be preferable to undirected and invasive testing.