Investigations
1st investigations to order
clinical exam
Test
The most common method to diagnose obesity is the BMI, defined as (weight in kg)/(height in m)².[1][2][3][39] The BMI is a reasonable determination of obesity in the vast majority of people, but it is not accurate in pregnancy or in people with a large amount of muscle mass (e.g., professional athletes). In addition, the BMI does not account for sex, age, or bone structure, all of which can influence the relative amount of body fat. Despite these drawbacks; however, the BMI remains the standard and usual test for the diagnosis of obesity in adults.
Result
obesity is defined as a BMI ≥30 kg/m²
Investigations to consider
FBC
Test
Routine screen for anaemia or thrombocytopenia in patients where these complications are suspected.
Result
normal, may show anaemia
serum transaminases
Test
Routine screen for evidence of liver dysfunction in patients where abnormalities are suspected
Result
normal, may be elevated if liver dysfunction
thyroid function tests
Test
Routine screen for hypothyroidism if clinically suspected.
Result
normal; free thyroxine (T4): low with hypothyroidism; thyroid-stimulating hormone (TSH): may be elevated with primary hypothyroidism, or normal or inappropriately low with central hypothyroidism
ECG
Test
Routine screen for signs of heart disease if suspected.
Result
normal, may show abnormalities associated with heart disease
abdominal ultrasound scan
Test
Routine screen for fatty liver, steatohepatitis.
Result
normal, may show evidence of fatty liver
polysomnography (sleep study)
Test
Routine screen for obstructive sleep apnoea where suspected.
Result
normal, may show signs of obstructive sleep apnoea
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