Last posting, we discussed definition of concerning weight loss: ≥5% of normal weight within 6 months [often less; urgency defined in terms of rapidity of loss]. And we identified clues in the history and physical which guide our work-up. But what about the patient whose H&P is stone-normal?
Among community-dwelling adults with involuntary weight loss, up to a third will have a malignancy, and even more may have a psychiatric etiology. But one study found that less than 2% of such neoplasms are occult; therefore, it’s not warranted to head straight to pan-CT [aka “Grope-o-gram”). A basic work-up as outlined below should nail the vast majority of causes of weight loss, or offer clues as to who may need aggressive testing.
So once you’ve convinced yourself that a patient has bona fide weight loss, and your H&P is unrevealing, order the following:
- Sed Rate [or CRP if you prefer]
- Chemistry Panel (Basic & Metabolic, including around 20 tests)
- HIV Antibody
- Prostate Specific Antigen (PSA) in man >50 (African-American >40)
- Chest X-Ray
The above tests are helpful in the following ways:
** CBC may reveal the various abnormalities:
- Anemia (microcytic): Obtain iron studies to confirm iron deficiency, then send to GI for upper & lower scopes (see posting Anemia-2)
- Anemia (normocytic): Justifies aggressive search for underlying infection or malignancy (see posting Anemia-3)
- Macrocytosis (high MCV): Marker for occult alcoholism; may suggest liver disease or hematologic malignancy (see posting Anemia-3)
- Leukocytosis: Seek underlying infection or malignancy
- Thrombocytopenia: Earliest finding in cirrhosis; test for HIV if not yet done
- Eosinophilia: Hematologic malignancies; certain parasites
** ESR / CRP: If very elevated, justifies aggressive search for underlying infection or malignancy. Think also of Crohn’s Disease.
** TSH: If <0.01 (or lab’s lower limit of detection), you’ve likely Dx’d Hyperthyroidism (see posting Hyperthyroidism)
** Chemistry Panel: Various abnormalities possible:
- Hyperglycemia: If very high, Diabetes is likely cause of wt. loss
- LFTs increased: Acute Hepatitis vs. Liver Metastases
- Low Albumin: In the absence of known cirrhosis, suspect malignancy. May reflect either nutritional deficiency, or negative acute phase reactant [non-specific marker, like increased ESR/CRP]
- Hypercalcemia: Order PTH and also PTH-related peptide (PTH-rp); the latter is increased in various malignancies. But first, be sure to adjust the calcium based on serum albumin. Consider a “normal” albumin as 4.0 g/dL — for every 1.0 increase or decrease in albumin, the calcium changes 0.8 mg/dL artifactually.
- Significantly-increased creatinine: Renal Failure vs. Multiple Myeloma
- Elevated Globulin: Order Serum & Urine Protein Electrophoresis (SPEP & UPEP) for Multiple Myeloma vs. chronic infection [if Globulin not included in chemistry panel, click for hint on Calculating Serum Globulin]
** LDH — If elevated, may be a marker for both malignancy and underlying pulmonary disease. If the chest x-ray is normal, the high LDH may justify a more aggressive search for cancer.
** HIV Antibody — Speaks for itself. Weight loss can be a pre-AIDS symptom of advancing disease. Some HIV patients, usually those with high viral loads, may be rapid progressors. Anyone with weight loss and even the least likelihood of HIV infection who hasn’t been tested in the last 2 years should have an antibody obtained.
** Prostate Specific Antigen — Screening PSAs are controversial, but here we’re talking about diagnosis. Any man over 50 y.o., or African-American man over 40, with weight loss should have a PSA.
** Chest X-Ray — A simple test to identify many lung cancers, virtually all non-viral lung infections, adenopathy due to lymphomas or sarcoidosis, and possible clues to interstitial lung disease. Weight loss with a normal chest x-ray virtually eliminates a pulmonary etiology, though a CT may be warranted in heavy smokers.
SUMMARIZING: a patient presents complaining of weight loss.
1. If we’re not particularly convinced, and don’t have much time [the patient was a walk-in], we perform a brief H&P, order a few simple tests (e.g. CBC, Chemistries), schedule them back in 2-3 weeks, explaining that we may need to do additional testing later.
2. On return, if we document progressive loss, we complete the H&P and the lab profile above.
Of course, if we can document or are convinced about significant weight loss from the outset, and to the extent we have time, the work-up is expedited.
3. If there’s any suggestion of upper abdominal pain, or nausea / vomiting, we give a therapeutic trial of high-dose PPI (for peptic ulcer). At follow-up, lower it to normal dose if it helped, since we’d have a likely Dx.
- But beware; PPI’s can relieve the pain of gastric cancer. If pain’s relieved but weight doesn’t improve rapidly, send to G-I for EGD to r/o gastric cancer.
4. If weight remains stable on follow-up, we reassure & continue to monitor.
5. If weight has continued to drop, our H&P is unrevealing in terms of clinical clues, and labs are normal, we explore psychiatric disorders, especially depression [see our posting Depression]. If we identify a condition, treat. And if not…
6. Unrevealing H&P, negative labs, no psych disease — if weight continues to decline, we can’t ignore it.
- Abdominal and pelvic CT would offer the best yield.
- Would certainly refer for colonoscopy if the patient is over 50 and hasn’t had one recently; otherwise, it’d be a long shot.
- Same with mammograms — obtain one in the 40-49 age group if you start routine screening at 50.
- Could do a cosyntrosyn stimulation test to r/o adrenal insufficiency, or send to Endocrine. But in the absence of key signs like orthostatic hypotension or generalized hyperpigmentation (new “suntan”), it’d be most unlikely.
Fortunately, for patients with weight loss, the vast majority of diagnoses will be identified through a decent H&P, plus basic lab tests.
Next posting, on to a heavier subject — weight gain.