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Cases
Hypoglycemia in Childhood
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Case
A 14-month-old girl is referred to a pediatric endocrinologist after she had 5 episodes of staring, limpness, and unresponsiveness beginning at 10 months of age. The episodes lasted 5-30 minutes. The first episode occurred when the child was hospitalized for a rotaviral infection. The other 4 occurred after several hours of fasting, though she was otherwise healthy. The child's blood glucose levels were measured during 2 of the episodes and found to be 43 and 47 mg/dL. A neurologist evaluated the girl and obtained an EEG, a head MRI, a serum ammonia measurement, a lactic acid concentration, an acyl carnitine profile, qualitative amino acid levels, and urine metabolic values. The results were all normal.
The child's past medical history is otherwise unremarkable. She was born at term with a weight of 3.5 kg and length of 50 cm (both in the 50th percentile). Her only surgery was for the placement of tympanostomy tubes to treat recurrent otitis media. She began crawling at 9 months and walking at 14 months.
The physical examination reveals a proportionate girl with a weight of 8.5 kg (10th percentile) and a length of 68.5 cm(<5th percentile). Further evaluation with the following tests produced normal results: morning cortisol level, insulin level, thyroxine (T4) level, thyroid-stimulating hormone (TSH) level, and oral glucose tolerance test. Her insulinlike growth factor-1 (IGF-1) level is undetectable.
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***** HINT *****
Growth delay.
***** ANSWER *****
Growth hormone deficiency: The child has classic symptoms of growth hormone deficiency in infancy. Growth hormone is one of the counterregulatory hormones, in addition to cortisol, glucagon, and epinephrine. Hypoglycemia in the setting of panhypopituitarism or combined growth hormone and adrenocorticotropic hormone (ACTH) deficiencies tends be more severe. However, hypoglycemia associated with isolated growth hormone deficiency can be significant, especially during periods of illness or fasting.
The clue in this patient's case was the deceleration in growth during her first year of life. Delays in the development of gross or fine motor skills can also be associated with this condition. The low IGF-1 level supports the diagnosis of growth hormone deficiency. This child subsequently underwent 2 growth hormone provocative tests, one with L-dopa and the other with clonidine. Both tests yielded growth hormone values far less than 10 ng/mL, which is considered diagnostic.
The patient's response to growth hormone therapy has been excellent, with total resolution of hypoglycemic symptoms and marked acceleration in linear growth. The patient's most recent growth parameters at age 4.5 years were a height of 108.7 cm (75th-90th percentile) and a weight of 18.7 kg (75th percentile). See the infant and childhood growth curves depicting the patient's response.
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Author:
Pamela A Clark, MD
Head, Section of Pediatric Endocrinology, Associate Professor, Department of Pediatrics, University of Louisville
Associate Professor, University of Nebraska and Creighton University, Departments of Neurology
Source
http://emedicine.com
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