Adenohypophysial disorders Flashcards
Describe the 50th centile
50% above, 50% below
What is normal growth
Follow the same centile.
If they suddenly switch from one centile to the other this could be a sign of abnormal growth, should investigate further- could be a sign of growth hormone deficiency- something has been acquired since birth
When does the inflexion point occur on the growth curve (dy/dx=0)
Post-puberty- no more growth
What happens during puberty
There is accelerated growth
Describe the key difference in delayed puberty
Point of inflexion happened later on- this is pathological and requires treatment.
What are the various causes of short stature
Malnutrition
Abuse (emotional deprivation, sleep deprivation).
Low levels of physical activity
Genetics- may naturally have a short stature
Genetics- dwarfism- growth not in proportion.
Laron dwarfism- gene deletion- no receptor for IGF-1.
Achondroplasia- cannot make cartilage- no ability to grow
Pituitary gland tumour (benign)
Autoimmune disease (fighting hypophycitis)- headache would accompany this
How do we design a GH stimulation test
Put the patient in a hypoglycaemic state by giving them insulin injections. Measure levels of growth hormone before and after. Levels of growth hormone should increase.
You could also ask the patient to perform some strenuous exercise, such as a sprint. However, it is difficult to standardise this test, and patients may not be able to perform the test at the desired activity to stimulate the release of growth hormone, thus increasing the risk of false positives.
Describe mid-parental height
The mid parental percentile calculates the expected height of an individual given their parents’ heights.
The first stage is to take a mean of the parental heights.
The mid parental height is calculated in males, by adding 7cm to the mean of parental heights; in females by subtracting 7cm. This gives the height expected at 18 years for the child, and this can be plotted on the percentile chart to predict the child’s height at the appropriate age. This can normally vary by two standard deviations, or 5cm each way