How reliable is an insulin test and C-peptide test? Our daughter was hypoglycemic [down to 15 mg/dl [0.8 mmol/l] at some points) and had an insulin level of 51,000 µu/ml with a C-peptide of 0.05. The doctor said it had to be exogenous insulin. She also said that insulin levels tend to list with glucagon stim tests, which it did not, but such high levels might preclude this and baby was sick and stores may have been depleted. It was ruled she was being given exogenous insulin, which she definitely was not. Her father is IDDM with occasional bouts of hypoglycemia himself. Should further testing be done?

We think the child has a strong likelihood of having Beckwith Wiedemann syndrome, but the parents have lost custody to this child because of the claim of exogenous insulin. Any input into this would be very helpful. Growth hormone and cortisol levels were always low too.

Beckwith syndrome is indeed associated with hypoglycemia in the first few days of life, but this is usually transitory. With regard to the laboratory tests, I think you need to talk them over again with the doctor because I can’t help feeling that there may have been some problem in communication. First of all, a blood glucose of only 15mg/dl [0.8 mmol/L] is very unusual indeed and would normally have precipitated significant central nervous system symptoms. The value for serum insulin of 51,000 µu/ml is approximately 1000 times the upper level for a normal fasting sample. C-peptide is normally reported in ng/ml, and if this was the case here, a level of.05 would be very low. I can therefore quite understand why the bizarrely high insulin level, together with the apparently low C-peptide and the low blood sugar, might have been interpreted as due to the administration of exogenous insulin. At the same time, I would have thought, in view of the drastic action taken, that it would be proper to repeat the tests if the laboratory has retained the original samples and certainly to clarify the units in which the results were reported. Beckwith Syndrome could be confirmed by finding an abnormality in the short arm of chromosome 11.

DOB

[Editor’s comment: This is truly a sad situation. The laboratory data as presented is highly suggestive of exogenous insulin administration. As indicated by the writer, the possibility of exogenous insulin administration by the father seems to exist, and the courts must have had some medical input (and probably some psychologic information also) to make the decision to take away custody of the child. Presumably, if the judge (or the lawyers for the losing side) had any questions about the validity of the lab data, or the pyschosocial issues surrounding the situation that would have been described in court, they would have would have insisted on reverifying the lab findings and getting additional psychologic evaluations.

There are too many “loose strings” about this case to try to resolve what actually is going on, without a full review of both the medical and court records. If the writer is unwilling to accept the judgement of the court, then perhaps seeking consultation with the pediatric endocrinology department of a local medical center would be the next step.

WWQ]