View source for Abnormal basal metabolic rate

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| name            = Abnormal basal metabolic rate
| field           = [[Endocrinology]]
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'''Abnormal basal metabolic rate''' refers to a high or low [[basal metabolic rate]] (BMR). It has numerous causes, both physiological (part of the body's normal function) and pathological (associated with disease).

==Causes==
===Physiological===
An abnormal basal metabolic rate is not necessarily indicative of disease; a number of physiological factors can alter the BMR by influencing [[metabolism|cellular metabolic activity]].<ref name=bijlani>{{cite book|title=Understanding Medical Physiology|page=383|edition=4th|first=R. L. |last=Bijlani|first2= S. |last2=Manjunatha|publisher=[[Jaypee Brothers]]|year=2010|isbn=9789380704814}}</ref> For instance, males are more likely than females to have a high BMR, and in women, the BMR may rise to abnormal levels during pregnancy or lactation.<ref name=marks>{{cite book|url=https://archive.org/details/marksbasicmedica0000lieb|url-access=registration|page=[https://archive.org/details/marksbasicmedica0000lieb/page/8 8]|title=Marks' Basic Medical Biochemistry: A Clinical Approach|first=Michael |last=Lieberman|first2= Allan D.|last2= Marks|publisher=[[Lippincott Williams & Wilkins]]|year=2009|isbn=9780781770224}}</ref> An individual's BMR varies greatly with age: infants and children typically have a high BMR, required for growth, while the elderly have a low BMR.<ref name=bijlani/> Tall, thin people have a higher BMR than their shorter counterparts, even with the same weight, due to the greater surface area of their skin.<ref name=bruyne>{{cite book|url=https://books.google.com/books?id=BN2PJSajgSIC&pg=PA150|page=150|title=Nutrition and Diet Therapy|first=Linda |last=DeBruyne|first2= Eleanor|last2= Whitney|first3= Kathryn|last3= Pinna|publisher=[[Cengage Learning]]|year=2007| isbn=9780495119166}}</ref> The metabolic rate also decreases during sleep and increases in exercise, and individuals who exercise regularly have a higher BMR than those who are sedentary.<ref name=bijlani/> Environmental temperature also has an effect: the BMR is increased in both heat and cold.<ref name=bruyne/>

===Pathological===
A common pathological cause for a high BMR is [[fever]], since a rise in body temperature increases the rate of cellular metabolic reactions.<ref name=bijlani/> It is estimated that for every degree [[Fahrenheit]] of rise in body temperature, the BMR increases by 7 percent.<ref name=bruyne/>

[[Thyroid disease]] also has a marked effect on BMR, since [[thyroid hormone]]s regulate the rate of cellular metabolism.<ref name=bruyne/> [[Hyperthyroidism]]—in which there is an increase in the production of thyroid hormones—leads to a high BMR, while [[hypothyroidism]]—in which thyroid hormones are depleted—causes a low BMR.<ref name=bijlani/>

Prolonged periods of abnormal nutrition cause an adaptive change in BMR; this helps the body to maintain a stable body weight in response to the change in food supply. In prolonged [[malnutrition]], the BMR declines, while in prolonged [[overnutrition]], the BMR is increased.<ref name=bijlani/> [[Cancer]] sometimes causes an increase in BMR, perhaps because the [[cancer cell]]s that form tumors have a high level of metabolic activity.<ref name=bijlani/>

==References==
{{reflist}}

== External links ==
{{Medical resources
|   ICD10       = R94.8
|   ICD9        = {{ICD9|794.7}}
}}
{{Abnormal clinical and laboratory findings}}

[[Category:Metabolic disorders]]
[[Category:Metabolism]]
[[Category:Symptoms and signs]]