Endocrine

Question 1

SIADH

Answer 1

• excess of ADH with increased permeability of renal distal tubule and collecting ducts results in increased water reabsorption and decreased urine production
• lab findings: serum Na <135, serum osmo <280, urine Na >30, urine osmo >200, urine spec gravity >1.020, urine output = 1ml/kg/hr
• management: restrict sodium, restrict fluid, normal saline, diuretics, monitor electrolytes
• causes: CNS injury, hypothalamus or pituitary issue, hepatic disease, high dose chemo

Question 2

Diabetes Insipidous

Answer 2

• antidiuretic effect, inadequate levels of antidiuretic hormone results in decreased water reabsorption, increase urine output, hypernatremia and dehydration
• lab findings: serum Na >150, serum osmo >295, urine Na <30, urine osmo <200, urine spec gravity <1.005, urine output >/= 4ml/kg/hr
• management: vasopressin or DDAVP, fluid replacement
• causes: CNS injury or infection, hypothalamus or pituitary disorders, tumor resection, renal defects

Question 3

Cerebral salt wasting

Answer 3

• anti natuiretic hormone excess results in sodium excretion into urine and diuresis with resulting hyponatremia and euvolemia or hypovolemia
• lab findings: serum Na <135, serum osmo <280, urine Na >30, urine osmo >200, urine spec gravity >1.010, urine output 2-3ml/kg/hr
• management: treat underlying problem, replace sodium slowly, likely hypovolemic –> maintain fluid intake
• causes: CNS injury or infection, endocrine disturbance, DKA, chronic lung disease, cardiac disease

Question 4

Diabetic ketoacidosis

Answer 4

• insulin deficiency where starvation state causes hyperglycemia and ketone formation with lactic acidosis from decreased tissue perfusion –> results in metabolic acidosis
• diagnosis: pH < 7.3, HCO3 <15
• management: NS bolus 20ml/kg, insulin drip 0.05-0.1u/kg/hr, add glucose when serum glucose is 250-300 or dropping faster than 100/hr, replace potassium and phosphorus, convert to subcutaneous when pH and HCO3 are normalized

Question 5

Congenital adrenal hyperplasia

Answer 5

• newborn with ambiguous genitalia, salt wasting and shock
• classic triad: hyperkalemia, hyponatremia and dehydration
• management with fluids and electrolytes, glucocorticoids and hydrocortisone