HYPOTHERMIA
Subnormal temperature is not usually a presenting finding, but when it
is found in cases of coma, hypothyroidism (myxedema coma) is the first thing
to rule out. Understanding the cause of this sign is best approached from a
physiologic standpoint. There are three basic reasons why a
temperature drops: absolute decrease in metabolic rate, decreased
circulation to the area where the temperature is being recorded, and
disorders of the thermoregulatory center in the brain.
-
Decreased metabolic rate. Hypothyroidism and hypopituitarism are
the principal conditions that fall into this category. Senility, starvation,
and chronic inanition may cause hypothermia due to a decreased metabolic rate.
Diabetes mellitus may cause hypothermia because of poor cellular absorption
of glucose.
- Poor circulation. Shock from any cause (hypovolemia, cardiogenic,
or neurogenic) falls into this category. Hemorrhagic shock, dehydration,
CHF, and adrenal insufficiency are all probably based on this mechanism.
With poor circulation, there is tissue anoxia and a reduced metabolism in
the skin and mucosa where the temperature is taken.
- Disorders of the thermoregulatory center. Cerebral thrombosis and
hemorrhage, certain pituitary tumors, and toxic suppression of this center
by barbiturates, alcohol, opiates, and
general anesthesia all fit into this category. Any case of prolonged coma
may cause hypothermia on this basis.
Approach to the Diagnosis
Establishing a definitive diagnosis of hypothermia depends heavily on
the interpretation of other symptoms and signs. A good history is invaluable
as well as laboratory studies including fasting blood sugar (FBS), thyroid
functions, electrolytes, BUN, and drug screens; in selected cases, a spinal
tap may be useful.
Other Useful Tests
-
CBC (anemia)
- Chemistry panel (uremia, liver disease)
- ECG (myocardial infarction, electrolyte disorder)
- Serum cortisol (Addison disease)
- CT scan of the brain (tumor, cerebral infarction)
- Serum FSH, LH, and growth hormone levels (pituitary insufficiency)
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.
Other Book Chapters Related to Hypothermia
Read excerpts from these other book chapters related to Hypothermia:
Medical Books Excerpts
- Hypothermia
- "Alarming Signs and Symptoms: Lippincott Manual of Nursing Practice Series" (2007)
- [ read ]
Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2008 Williams & Wilkins.
More About Causes of Hypothermia
» Next page:
Medications causing Hypothermia
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