Otonkoski et al described an autosomal-dominant syndrome of hypoglycemia after physical exercise associated with hyperinsulinemia (exercise-induced hyperinsulinism, or EIHI). Infusion of pyruvate in these patients can trigger release of insulin. The authors are from Haartman Institute at the University of Helsinki, University Children's Hospital in Dusseldorf and Karolinska Institute in Stockholm.


Clinical features:

(1) symptomatic hypoglycemia after strenuous physical exercise

(2) presence of increased serum insulin levels during the hypoglycemia

(3) intravenous infusion of pyruvate results in an excessive release of insulin (positive pyruvate test)

(4) presence in parents and other family members in an autosomal dominant pattern of inheritance


Pyruvate test:

(1) The patient is placed on an overnight fast.

(2) A baseline serum insulin level is drawn.

(3) The dose of pyruvate to infuse is 13.9 mmol per 1.73 square meters BSA (molecular weight pyruvic acid is 88.06 g; for sodium pyruvate 110.05 g). The dose for an individual patient would be:


dose in mmol = (body surface area in square meters) * 13.9 / 1.73 =

= (body surface area in square meters) * 8.0347


(4) After infusing the pyruvate serum insulin levels are drawn every minute for the first 5 minutes and then at 10 and 15 minutes.

(5) A patient with EIHI has much higher peak insulin levels measured at 1 and 3 minutes than the values seen normal control.

(5a) A normal person will show little change in serum insulin levels, with a relatively flat curve.

(5b) An affected patient will show a sharp rise at 1 minute after infusion with a peak at 3 minutes, followed by a gradual decline over 10-15 minutes. The peak will be much higher (usually 4-6 times) than the pretest baseline.


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