WEIGHT LOSS
WEIGHT LOSS: Excerpt from Differential Diagnosis in Primary Care
As noted in Table 62, the diagnostic analysis of weight loss
is best accomplished by applying physiology. Food and oxygen must
be properly and regularly brought into the body (intake), properly absorbed
and circulated to the cells, and properly used; the waste products must then
be excreted in order for weight to be maintained. The storage of food is
essential to maintain weight when food is not being regularly ingested.
Finally, there must be minimal excretion of sugar, protein, electrolytes,
and water to maintain weight. Let us explore each of these physiologic
functions for possible alterations.
WEIGHT LOSS
|
| Physiologic Analysis |
|
| Decreased
| Decreased
| Decreased
| Impaired |
| Intake
| Absorption
| Circulation
| Storage |
|
| Oxygen |
Asthma Emphysema Central nervous system hypoventilation |
Sarcoidosis Pulmonary fibrosis of other causes |
Anemia of various causes Congestive heart failure | |
|
| Food and Drink |
Vomiting of various causes Kwashiorkor Obstruction by carcinoma of esophagus or stomach cardiospasm Anorexia nervosa Cerebral arteriosclerosis or degeneration Chronic alcoholism |
Sprue Nontropical sprue Intestinal parasite Scleroderma Blind loop syndrome Pancreatitis
| | Cirrhosis Glycogen storage disease Hypopituitarism |
|
| Vitamins |
Scurvy Pellagra Alcoholism |
Diphyllobothrium latum Regional ileitis Gastric atrophy Pernicious anemia Sprue | |
|
WEIGHT LOSS
|
| Physiologic Analysis |
|
| Increased | Impaired | Decreased
| Increased |
| Utilization | Utilization | Excretion | Excretion |
|
| Oxygen |
|
|
Cyanide poisoning and other exogenous toxins Electrolyte disorders |
Pulmonary disease, chronic obstructive | |
|
| Food and Drink |
Hyperthyroidism Fever due to infection or neoplasm Hypermetabolism in malignancy, chronic infection (e.g., tuberculosis) Chronic inflammation of rheumatoid arthritis |
Decreased utilization Various muscle and central nervous system diseases |
Jaundice |
Aminoaciduria/renal glycosuria Hypocalcemia of various causes Hypokalemia Diabetes insipidus Albuminuria |
| |
|
|
| |
|
|
|
| |
| |
| |
| |
| |
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Decreased intake of food results from any disease associated with
vomiting, upper intestinal obstruction (e.g., carcinoma of the pyloris), and
esophageal obstruction (cardiospasm and carcinoma of the esophagus).
Starvation is not uncommon even today, particularly in the elderly
population trying to stretch their Social Security checks. Depression,
anorexia nervosa, and other psychiatric disturbances may cause weight loss
by decreased intake. Central nervous system (CNS) diseases such as cerebral
arteriosclerosis may cause disinterest in food and poor chewing and
swallowing. Chronic alcoholics do not eat. The absence of one vitamin, as in
scurvy or pellagra, may cause weight loss.
Decreased intake of oxygen occurs in asthma, emphysema, and other
respiratory disorders as well as in CNS diseases that may cause
hypoventilation (poliomyelitis).
Decreased absorption of food and electrolytes are common in
malabsorption syndrome, pancreatitis, intestinal parasites, and blind loop
syndrome. Regional ileitis and tapeworms reduce the absorption of vitamins.
The decreased circulation of oxygen is probably the main cause of
wasting in CHF, but certainly congestion of the liver and decreased
excretion of waste products may play a role. Severe anemia of various causes
will inevitably decompensate the delivery of oxygen to the tissues.
The weight loss of cirrhosis (numerous etiologies) is probably due to
impaired storage of fat and sugar for use when it is most needed,
but the ability to convert protein to sugar and vice versa is also impaired.
In glycogen storage and lipid storage diseases, a one-way trip of sugar or
fat into the liver is a prominent factor contributing to weight loss.
Probably the most common causes of weight loss today are due to the
increased use of food in hyperthyroidism and malignancies, but the
hypermetabolism of fever and any inflammatory condition (rheumatoid
arthritis) is also common.
Neurologic and muscular diseases cause wasting and thus decrease the
use of sugar. Impaired use of sugar in diabetes mellitus and other
endocrinopathies is a significant cause of weight loss. Various toxins and
electrolyte disorders may block the tissue uptake of oxygen (cyanide
poisoning, and so forth) and cause weight loss. Disorders of
excretion also commonly play a role; thus, one should always look for
uremia, pulmonary emphysema, and jaundice.
Finally, there are many disorders already mentioned associated with
albuminuria and glycosuria that may be classified under increased excretion
of metabolic substances; these, of course, contribute to weight loss. The
numerous aminoacidurias and diabetes insipidus should be remembered in this
regard.
Approach to the Diagnosis
Weight loss rarely occurs as the only symptom. When it seems to be the
only symptom, there is almost invariably a psychiatric disorder such as
depression or anorexia nervosa to explain it. More often the diagnosis of
weight loss can be made by the other associated symptoms. For example,
weight loss with a good appetite, polyuria, and polydipsia should point to
hyperthyroidism and diabetes mellitus. Weight loss with weakness and
polydipsia but no increase of appetite points to diabetes insipidus. Weight
loss, weakness, and loss of appetite suggest the possibility of a
malignancy, chronic infectious disease, or endocrine disorder. Weight loss
with significant local or generalized lymphadenopathy suggests chronic
leukemia, lymphoma, sarcoidosis, or a chronic infectious disease process.
Weight loss with hyperpigmentation of the skin suggests Addison disease or
hemochromatosis. Weight loss with significant pallor of the skin and mucus
membranes suggests a diagnosis of anemia, malabsorption syndrome, and
malignancy. Weight loss with jaundice suggests alcoholic cirrhosis, chronic
hepatitis, primary or metastatic neoplasm of the liver, or biliary
cirrhosis. The initial workup of weight loss should include a CBC,
sedimentation rate, chemistry panel, thyroid profile, urinalysis, stool test
for occult blood, chest x-ray, and flat plate of the abdomen. If there is
fever, the workup of this symptom can be pursued . Other tests may be ordered depending on which
disease is suspected. Before ordering a battery of tests, it may be wise to
get a psychiatric consult and make sure there is not a “supratentorial”
cause for the problem.
Other Useful Tests
-
Tuberculin test (tuberculosis)
-
Glucose tolerance test (diabetes mellitus)
-
Serum amylase and lipase levels (chronic pancreatitis,
pancreatic neoplasm)
-
Drug screen (drug abuse)
-
HIV antibody titer (AIDS)
-
Stool for fat and trypsin (malabsorption syndrome)
-
Stool for ova and parasites (parasites infestation)
-
d-Xylose absorption test (malabsorption syndrome)
-
Urine 5-hydroxyindole acetic acid (5-HIAA) (carcinoid syndrome,
malabsorption syndrome)
-
Bone scan (metastatic malignancy)
-
CT scan of the abdomen (malignancy, abscess)
-
Lymphangiogram (Hodgkin lymphoma, metastatic malignancy)
-
CT scan of the brain (pituitary tumor)
-
Lymph node biopsy (lymphoma, malignancy)
-
Serum antidiuretic hormone (ADH) level (diabetes insipidus)
-
Serum cortisol level (Addison disease, hypopituitarism)
-
Serum growth hormone, LH or FSH (Simmonds disease)
Pictures
Book Source Details
- Book Title: Differential Diagnosis in Primary Care
- Author(s): R. Douglas Collins MD, FACP
- Year of Publication: 2007
- Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2007 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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