The posterior pituitary stores two hormones produced in the hypothalamus: Antidiuretic hormone (ADH, also known as vasopressin) and oxytocin. Oxytocin stimulates milk ejection or “let down” in lactating women. In pharmacological doses, it can be used to initiate or improve uterine contractions in labor.
ADH possesses antidiuretic, hemostatic, and vasopressor properties. Posterior pituitary disorders can occur secondary to head trauma or surgery, metastatic cancer, lymphoma, disseminated intravascular coagulation, or septicemia. Posterior pituitary disorders that are seen clinically involve ADH release and include diabetes insipidus, which results from insufficient secretion of ADH, and syndrome of inappropriate antidiuretic hormone (SIADH), which occurs with excessive secretion of ADH. Both conditions can now be treated pharmacologically.
Diabetes insipidus is characterized by the production of a large amount of dilute urine containing no glucose. Blood becomes concentrated and blood glucose levels are higher than normal, and the patient presents with polyuria (lots of urine), polydipsia (lots of thirst), and dehydration. With this rare metabolic disorder, patients produce large quantities of dilute urine and are constantly thirsty. Diabetes insipidus is caused by a deficiency in the amount of posterior pituitary ADH and may result from pituitary disease or injury (e.g., head trauma, surgery, tumor). The condition can be acute and short in duration or it can be a chronic, lifelong problem.
SIADH presents with fluid retention, dilution of the blood and all of the blood elements, serious issues with water balance and fluid volume. This disorder is now treated with drugs that block the ADH or vasopressin receptors, so water is no longer retained and urine is produced, helping to restore water balance. Keeping the fluid balance in check can be very tricky and patients receiving these drugs need to be closely monitored in the hospital.
1. A client withdiabetesinsipidus is takingantidiuretic hormone. Which of the following symptoms would alert the need to decrease the dosage?
A. Alopecia.
B. Jaundice.
C. Diarrhea.
D. Drowsiness.
2.Desmopressinacetate (DDAVP) is given to a patient withdiabetesinsipidus. Which of the following therapeutic response should you expect?
A. Decreased blood pressure.
B. Decreased attention span.
C. Decreased urinary output.
D. Decreased blood sugar.
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答案 Answers 1. D. Drowsiness. Rationale: One of the side effects of taking antidiuretic hormone is water intoxication which is manifested by a headache, drowsiness, light-headedness, and shortness of breath. This could indicate the need to reduce the dosage. Options A, B, and C are not related signs to this medication. 2.C. Decreased urinary output. Rationale: The therapeutic response of this medication is decreased urine output because it promotes renal conservation of water. Options A, B, and D are unrelated effect to this medication.
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