2. Serious, involuntary weight loss indicates serious illness underneath it -Loss of >10% of body weight in the last 6 months -Weight loss should not be considered idiopathic even if no illness is found underneath in first evaluation -The patient should be followed- up with intervals until the occult disease becomes appearent

3. The Mechanisms of Weight Loss -Increase in energy consumption -Increase in energy loss -Decrease in food intake One or more than one of these three mechanisms may be found in the same patient

4. The Occasional Causes of Weight Loss A. Increase in energy consumption Hyperthyroidism Feochromocytoma Extreme exercise

5. B. Increase in energy loss Diabetes Mellitus Malabsorption syndromes

6. C. Decrease in Food Intake(I) Congestive heart failure Chronic obstructive pulmonary disease Chronic hepatic disease Neurologic diseases Inflammatory/autoimmune diseases

7. Decrease in Food Intake (II) Cancer Infections (HIV,Tuberculosis, Endocarditis) Hypercalcemia (Malignant diseases, Hyperparathyroidia, Sarcoidosis) Uremia Gastrointestinal system obstruction Anorexia Nervosa

8. Decrease in Food Intake(III) Adrenal Insufficiency (Primary, Secondary) Pernicious Anemia Alzheimer’s Disease Depression

9. The most frequent cause for weight loss is generally decrease in food intake Decrease in food intake is generally due to loss in apetite Still, it may be due to obstruction of eosephagus or stomach with a stricture or an infiltrative or obstructive mass

10. Increase in Energy Loss may be due to: Diabetes Mellitus with glucosuria Malabsorption with steatorhea The most frequent cause for steatorhea; Chronic pancreatitis in alcoholics Intestinal lymphoma Celiac Disease, inflammatory bowel disease Islet cell tm Obstruction of biliary tract

11. If weight loss occurs inspite of increased food intake Diabetes Mellitus Hyperthyroidism Malabsorption Rarely leukemias and lymphomas cause weight loss without anorexia

12. In Adolescents Diabetes Mellitus Hyperthyroidism Anorexia Nervosa Infections (HIV etc.)

13. In Older People; Most frequent cause: Cancer Psychiatric disease: Alzheimer’s disease, depression

14. In asymptomatic patients weight loss only may be a sign for a occult disease Cancer (Gastrointestinal, pancreatic, hepatic malignancies cause weight loss in the early period) Infectious diseases (sometimes only with weight loss): Tuberculosis, HIV infection, fungal diseases, bacterial endocarditis, hepatitis Alzheimer’s disease, depression, eating disorders in the early period

15. Pernicious anemia: May cause anorexia before haematologic changes appear Adrenal insufficiency: In the early period; before electrolyte imbalance, hyperemesis, vomiting and hypotension appears, it may present with weight loss Parasite infections: People coming from foreign countries

16. Evaluating Involuntary Weight Loss Anamnesis Physical examination

17. Laboratory Tests Preliminary laboratory tests: Full blood count, sedimentation, urine analysis, blood biochemistry, TSH, HIV test in patients with risk, chest radiography, stool analysis for occult blood

18. Secondary screening Abdominal CT In the presence of hypercalcemia: Mammography, serum protein electrophoresis, PTH-related peptide, ACE (angiotensin converting enzyme), 1,25 dihidroxy-vitamin D If there is iron deficiency anemia or melena or doubt for inflammatory bowel disease; colonoscopy Upper gastrointestinal tract bleeding or dysphagia: upper gastrointestinal tract endoscopy

19. Weakness,pigmentation,hyponatremia/hyperkalemia: short ACTH test Unknown fever with weight loss: blood culture Blood culture (-): bone marrow biopsy Chronic diarrehea: fat in 72 hours stool Headache, neurologic symptoms, endocrine insufficiency: Cranial CT or MRI B 12 vitamine

20. For each patient presenting with weight loss, first stage laboratory tests should be performed Blood chemistry establishes electrolyte abnormalities which indicates diabetes mellitus, hypercalcemia, renal insufficiency, hepatic disease, adrenal insufficiency and gastrointestinal system disease TSH is used to omit hyperthyroidism Chest radiography should always be performed Stool test for occult blood and HIV test in patients with high risk are mandatory

21. If the reason for weight loss can not be diagnosed after these examinations, secondary screening is undertaken. Abdominal CT is generally performed first Other procedures change according to the presence of hypercalcemia, Fe deficiency anemia, fever and electrolyte imbalance, If diarrhea exists, fat analysis in 72 hours stool test and measurement of hormones like gastrine, somatostatine and glucaghone are performed

22. In unexplained weight loss, B 12 vitamine level should be analyzed even in the absence of anemia and macrositosis In the presence of serious, uncommon headache, cranial CT is indicated regardless of the neurologic symptoms Back pain accompanied by fever and neurologic deficits may indicate paraspinal and epidural abscess (due to tbc or stafilococcus in IV drug users)

23. SUMMARY Weight loss generally indicates a serious illness underneath it The patient should be followed up closely and tests should be carried on when the cause is not found Patient should be followed up monthly with physical examinations and laboratory tests if the cause is still not found The follow-up interval can be longer if the cause is not found in 6 months