Low body fat mass and hormone levels ?

An 11-year-old girl is presented at the clinic with reports of frequent fainting and lethargy. The girl is 5 ft tall and weighs 80 lb. Skin fold tests show an abnormally low percentage of body fat mass. Which of the following hormones is likely to be severely diminished in this patient?

A. Cortisol

B. Epinephrine

C. Glucagon

D. Insulin

E. Thyroid

Answer- The correct answer is D.

The patient has low body weight and fat mass and there are frequent fainting attacks. Apparently her condition is consistent with a low energy state that might be due to poor diet or anorexia nervosa which is very common in girls of this age. Reason may be any but it is a state of prolonged fasting or starvation. Blood glucose level should be low in such a state as evident from frequent fainting spells. During such a condition, circulating insulin levels should be low, whereas counter regulatory hormones (e.g., glucagon, epinephrine, and cortisol) should be elevated.

Prolonged fasting may result from an inability to obtain food, from the desire to lose weight rapidly, or in clinical situations in which an individual cannot eat because of trauma, surgery, neoplasms, burns etc. In the absence of food the plasma levels of glucose, amino acids and triacylglycerols fall, triggering a decline in insulin secretion and an increase in glucagon release. The decreased insulin to glucagon ratio, and the decreased availability of circulating substrates, make this period of nutritional deprivation a catabolic state, characterized by degradation of glycogen, triacylglycerol and protein. Gluconeogenesis becomes the main mechanism for maintenance of blood glucose homeostasis during prolonged fasting (Figure).

glucose homeostasis

Figure- Maintenance of blood glucose is vital for life. The blood glucose levels are maintained by dietary glucose during fed state, through glycogenolysis during early fasting and by gluconeogenesis during prolonged fasting or starvation. The substrates for gluconeogenesis are obtained from the products of catabolism such as carbon skeleton of amino acids, glycerol, lactate and intermediates of TCA cycle.

As regards other options

Cortisol- It exerts an anti insulin effect by inhibiting cellular glucose uptake. It promotes gluconeogenesis during catabolic state. Its secretion is suppressed by hyperglycemia and stimulated by hypoglycemia. In the given situation, cortisol level should be high.

Epinephrine- It promotes hyperglycemia by stimulating glycogenolysis. It also exerts anti insulin effect, depresses insulin secretion and promotes lipolysis. In the current state of hypoglycemia the epinephrine level cannot be low, instead it should be high.

Glucagon- It opposes insulin action by stimulating glycogenolysis, gluconeogenesis and lipolysis. Its level is also expected to be elevated in the given patient with presumed hypoglycemia.

Thyroid- It increases blood glucose level by promoting dietary glucose absorption.

Thus out of all the most suitable option is D- Low insulin level.

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