HY USMLE Q#4 Renal Concept Step 2CK

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Step 2ck/ 3 level (inspired from UWORLD)

A 40-year-old woman presents with elevated blood pressure of 160/90 mmHg, family history consistent with many relatives having renal fialure. She has occasional epsidoes of pain in her flanks but attributes it to muscle tension. Her HR is 80/ min. Herrinalysis shows RBC, proteinuria and ECG show ST -T wave non-specific changes. Serum K+ is 4.5 meq/l. What is the next best step in management ?

1. Check Serum Metanephrines

2. Obtain twice-weekly home blood pressure measurements

3. Measure plasma renin activity

4. Obtain Renal Ultrasound

5. Educate on Lifestyle modifications and follow-up in 6 to 8 weeks.

Explanation:

✅ D. Obtain Renal Ultrasound. The patient has ADPKD. Additionally, the patient has proteinuria and hematuria due to damage to the capillaries. Also, she has a family history of renal failure; hence, supporting the diagnosis of ADPKD. The reason we get high blood pressure in a patient with ADPKD is due to the cysts develop and expand in the kidneys, they can disrupt normal kidney function and blood flow. This can lead to the activation of the renin-angiotensin-aldosterone system; hence, increasing blood pressure.

❌ A. Check Serum Metanephrines --> We do this to diagnose pheochromocytoma.
1. Paroxysmal hypertension = pheochromocytoma doesn’t continuously release catecholamines they release them in bursts. Also, there can be triggers like stress which lead to the release of epinephrine.
2. Palpitation = epinephrine binds to beta 1
3. Perspiration = Perspiration in pheochromocytoma occurs due to excessive secretion of catecholamines which overstimulate the SNS. Catecholamines bind to receptors on the sweat glands, particularly the eccrine sweat glands, which are responsible for thermoregulation and sweating. Recall the sweat glands will bind acetylcholine at the post-synaptic.
4. Pain in Head = epinephrine binds to alpha 1
5. Pallor = epinephrine binds to alpha 1
Pheochromocytoma and paragangliomas are rare.

1. "pheo-": means “dark" or "dusky." It refers to the dark staining of the cells that can be observed under a microscope
2. "chromo-": This part is derived from the Greek word "chroma," meaning "color."
3. "cytoma": This suffix comes from the Greek word "kytos," meaning "cell," and "-oma," which denotes a tumor.
Rule
- 10% Malignant
- 10% bilateral/Multiple
- 10% in Children
- 10% familial
- 10% recurrence
- 10% extra-adrenal
- 10% discovered incidentally

Pheochromocytoma =
Paraganglioma doesn't have phenyl n methyl transferase hence no conversion from NE and Epi

❌ B. Obtain twice-weekly home blood pressure measurements. This refers to white coat hypertension; however, this patient has a lot of long-term changes like ST and T wave, proteinuria, RBC, and bilateral flank fullness, hence further investigations are required.
❌ C. Measure plasma renin activity --> Primary hyperaldosteronism where Potassium will be low due to aldosterone cause causing secretion of potassium from the principal cells of the collecting duct. Aldosterone stimulates the Na⁺/K⁺-ATPase pump on the basolateral membrane and increases the expression of epithelial sodium channels (ENaC). Here is another key point. Apical membrane = faces the tubular lumen (i.e., urine side). The basolateral membrane = faces the interstitial fluid and blood (i.e., peritubular capillaries).
❌ E. Educate on Lifestyle modifications and follow-up in 6 to 8 weeks. --> Patients with essential hypertension are often treated with lifestyle modifications. This patient with evidence of long-standing hypertension at a relatively young age and flank fullness should undergo further evaluation with renal ultrasonography.