Download Chapter 24 Nephrogenic diabetes insipidus is thought to be an X

Chapter 24
1. Nephrogenic diabetes insipidus is thought to be an X-linked recessive disease. It is not
seen in Charles’s sisters because the father is normal and the sisters would inherit an X
chromosome with the normal gene from their father. Neither of the parents has the
disease because each inherited an X chromosome with a normal gene from one parent.
The mother must be a carrier since Charles has the disease. If Charles has a baby
brother, there is a 50% chance that his brother will have the disease, because he has
equal chances of inheriting either the mother’s X chromosome with the normal gene or
the one with the defective gene.
2. Charles’s diagnosis of nephrogenic diabetes insipidus is supported by the following:
increased frequency of feeding and urination; low urine specific gravity; dehydration as
evidenced by the lack of skin turgor, sunken fontanels, and dry mucous membranes;
elevated blood ADH; and lack of response to ADH in the water deprivation test.
3. Charles’s mother should be told that he will not require daily injections of insulin because
he does not have "that type of diabetes." His diet must include adequate water, but his
carbohydrate consumption will not be restricted.
4. As Charles gets older, he should be counseled about the disease and encouraged to
drink adequate amounts of fluid to maintain hydration.
5. If Charles fails to remain hydrated, he will exhibit the symptoms of dehydration and
hypernatremia. This could lead to a wide variety of signs and symptoms, including
vomiting, seizures, fever, convulsions, brain damage, and possibly even death.
6. Normally, the level of ADH is regulated by negative feedback inhibition. High blood
osmolarity stimulates ADH secretion, ADH stimulates water retention, blood osmolarity
falls as water is ingested, and the falling osmolarity suppresses ADH secretion. In
nephrogenic diabetes insipidus, however, the ADH has no effect, so blood osmolarity
does not return to normal and ADH secretion continues to rise without inhibition.
7. Nephrogenic diabetes insipidus more closely resembles type II diabetes mellitus. In both
diseases, the hormone is secreted, but the cells lack the ability to respond. In neither
instance does the patient respond to hormone therapy.
8. (c) A patient with hyponatremia would be given a slow infusion of hypertonic saline.
9. (a) Acidosis developed during the cardiac arrest because Jack’s cells began producing
lactic acid through anaerobic fermentation and the retention of carbon dioxide. (b)
Sodium bicarbonate would act as a buffer and remove excess hydrogen ions, leading to
an increase in pH. (c) The hypernatremia resulted from the sodium in the I.V. sodium
bicarbonate. (d) The hypernatremia could be corrected by giving Jack water or 5%
dextrose in water intravenously or orally.
10. Patient A has compensated metabolic alkalosis. Patient B has compensated respiratory
acidosis. Patient C has uncompensated metabolic acidosis.