Metabolism
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A hypoglycaemic adolescent with an enlarged liver and gout
AP is a 16 year old boy. As an infant he was liable to convulsions if he was not fed at regular intervals. He has a greatly enlarged liver, which is readily palpable. For the last year he has suffered increasingly from gout, with deposition of crystals of uric acid in joints.
The following results were obtained on blood samples taken after an overnight fast:
glucose (mmol /L) |
insulin (mU /mL) |
non-esterified fatty acids (mmol /L) |
|
| AP | 2.2 |
2.0 |
2.08 |
| 10 age-matched control subjects | 4.0 ± 0.16 |
9 ± 0.7 |
0.71 ± 0.08 |
What conclusions can you draw from these results?
He has very low plasma glucose in the fasting state. Indeed, this is close to the level at which we might expect to see disturbance of consciousness or convulsions.
His plasma insulin is very low, presumably as a result of the low circulating concentration of glucose. It is unlikely that his problem is failure to secrete insulin (i.e. diabetes mellitus), since in this case we would expect to see a high plasma concentration of glucose with low insulin.
His plasma free fatty acids are very high in the fasting state. This would be expected from the low plasma glucose, since fatty acids will be mobilised from adipose tissue to provide an alternative fuel. We are not given any data, but we would expect his plasma ketone bodies (acetoacetate and hydroxybutyrate) to be high as well.
Although neither the enlarged liver nor the hypoglycaemia with low plasma insulin is typical of diabetes mellitus, in order to be sure he was given an oral dose of 1 g of glucose /kg body weight, and his plasma glucose was measured over 4 hours afterwards - a standard oral glucose tolerance test.
