ITE Nephrology and Hypertension 3 — Questions and Answers
Question 1: A 25-year-old woman is found to have BP of 170/100 mmHg on routine exam. Labs show hypokalemia, suppressed plasma renin activity, and elevated aldosterone. CT shows no adrenal mass. What is the best next diagnostic step?
- Renal artery Doppler ultrasound
- Adrenal vein sampling (Correct answer)
- 24-hour urine metanephrines
- MRI of the pituitary
Correct answer: Adrenal vein sampling
Adrenal vein sampling is the gold standard for differentiating unilateral aldosterone-producing adenoma from bilateral adrenal hyperplasia when CT is non-diagnostic.
Question 2: A 58-year-old man on hemodialysis for 8 years presents with bone pain and a serum calcium of 11.2 mg/dL, phosphorus of 5.8 mg/dL, and intact PTH of 850 pg/mL. What is this condition called and what surgical intervention may be needed?
- Secondary hyperparathyroidism; parathyroidectomy if refractory to cinacalcet
- Tertiary hyperparathyroidism; parathyroidectomy if refractory to cinacalcet (Correct answer)
- Adynamic bone disease; bisphosphonate therapy
- Primary hyperparathyroidism; single-gland parathyroidectomy
Correct answer: Tertiary hyperparathyroidism; parathyroidectomy if refractory to cinacalcet
Tertiary hyperparathyroidism occurs in long-term dialysis patients when autonomous PTH hypersecretion persists and may require parathyroidectomy if calcimimetics fail.
Question 3: A 48-year-old HIV-positive man on tenofovir disoproxil fumarate presents with a proximal renal tubular acidosis, glucosuria with normal serum glucose, hypophosphatemia, and hypokalemia. What syndrome does this represent?
- Bartter syndrome
- Gitelman syndrome
- Fanconi syndrome (Correct answer)
- Type 4 renal tubular acidosis
Correct answer: Fanconi syndrome
Tenofovir disoproxil fumarate can cause mitochondrial toxicity in proximal tubular cells, leading to Fanconi syndrome with global proximal tubule dysfunction.
Question 4: A 35-year-old woman with lupus nephritis class IV on mycophenolate and prednisone has a serum creatinine rise from 1.1 to 2.4 mg/dL over 3 months with worsening proteinuria. What is the best next step?
- Add hydroxychloroquine
- Switch mycophenolate to cyclophosphamide
- Repeat kidney biopsy (Correct answer)
- Add belimumab
Correct answer: Repeat kidney biopsy
A repeat kidney biopsy in lupus nephritis is essential to determine whether the class has transformed, activity has increased, or chronic scarring has developed before changing therapy.
Question 5: A 66-year-old man with hypertension is started on chlorthalidone. Two weeks later he reports muscle cramps. Labs: Na 138 mEq/L, K 3.0 mEq/L, Cl 94 mEq/L, HCO3 29 mEq/L, urine Cl 60 mEq/L. What acid-base disorder is present?
- Metabolic acidosis with respiratory compensation
- Metabolic alkalosis with appropriate respiratory compensation (Correct answer)
- Respiratory alkalosis with renal compensation
- Mixed metabolic alkalosis and respiratory alkalosis
Correct answer: Metabolic alkalosis with appropriate respiratory compensation
Thiazide diuretics cause metabolic alkalosis via volume contraction, increased aldosterone, and direct H+ and K+ loss in the collecting duct.
Question 6: A 72-year-old woman with stage 4 CKD is found to have serum bicarbonate of 18 mEq/L. Which intervention has been shown to slow CKD progression in addition to correcting the acidosis?
- Sodium bicarbonate supplementation (Correct answer)
- Dietary protein restriction alone
- Furosemide to reduce sodium load
- Calcium carbonate as a phosphate binder
Correct answer: Sodium bicarbonate supplementation
Alkali therapy with oral sodium bicarbonate has been shown in multiple trials to slow GFR decline in CKD patients with metabolic acidosis.
Question 7: A 29-year-old man presents with painless hematuria. Urine microscopy shows dysmorphic RBCs and RBC casts. Serum complement C3 and C4 are normal. Kidney biopsy shows mesangial IgA deposits. His serum IgA level is elevated. What triggers commonly cause gross hematuria episodes in this condition?
- Streptococcal pharyngitis with a 2-3 week latency
- Concurrent upper respiratory infections (synpharyngitic hematuria) (Correct answer)
- NSAIDs use
- Vigorous exercise only
Correct answer: Concurrent upper respiratory infections (synpharyngitic hematuria)
IgA nephropathy classically causes synpharyngitic hematuria (gross hematuria coinciding with mucosal infection) in contrast to post-streptococcal GN which has a latency period.
ITE Nephrology and Hypertension 3
A 25-year-old woman is found to have BP of 170/100 mmHg on routine exam.
Labs show hypokalemia, suppressed plasma renin activity, and elevated aldosterone.
CT shows no adrenal mass.
What is the best next diagnostic step?