What medication should be discontinued in a patient with hypertension, hyperlipidemia, and chronic lower back pain, presenting with weakness, fatigue, nausea, decreased urination, and impaired renal function, who is currently taking carvedilol, hydrochlorothiazide, atorvastatin, duloxetine, and oxycodone?

Discontinue Hydrochlorothiazide Immediately

Hydrochlorothiazide must be discontinued in this patient presenting with acute kidney injury (creatinine 1.9, BUN 49, decreased urine output) because thiazide diuretics become ineffective and potentially harmful when GFR falls below 30 mL/min, and they can worsen renal function in the setting of volume depletion. 1

Clinical Reasoning for Acute Kidney Injury

This patient presents with classic acute kidney injury (AKI):

• Elevated creatinine (1.9 mg/dL vs. normal 6 months ago) 1
• Elevated BUN (49 mg/dL) with BUN:creatinine ratio >20:1 suggesting pre-renal azotemia 1
• Oliguria (decreased urination) 1
• Symptoms of weakness, fatigue, and nausea consistent with uremia 2
• Mild metabolic acidosis (bicarbonate 20 mEq/L) and hyponatremia (sodium 132 mEq/L) 1

The estimated GFR based on creatinine 1.9 is approximately 35-40 mL/min, placing him in the severe CKD range where thiazides lose efficacy 1.

Why Hydrochlorothiazide is the Culprit

Ineffectiveness in Renal Impairment

• Thiazide diuretics lose effectiveness when creatinine clearance falls below 30 mL/min and should be replaced with loop diuretics 1
• Guidelines explicitly state that hydrochlorothiazide becomes ineffective in severe renal impairment (GFR <30 mL/min) 1
• In patients with moderate-to-severe CKD, loop diuretics are preferred over thiazides 3, 4

Mechanism of Harm

• Thiazides cause pre-renal azotemia and further deterioration of renal function through volume depletion 1
• The patient likely became volume depleted during travel (decreased oral intake, possible dehydration), and hydrochlorothiazide exacerbated this by continuing to promote sodium and water loss 1
• NSAIDs combined with thiazides significantly increase nephrotoxicity risk, and this patient is on oxycodone which may have been combined with over-the-counter NSAIDs for back pain 1

Guideline Recommendations

• Hydrochlorothiazide should be discontinued during acute illness, dehydration, or when renal function deteriorates to GFR <30 mL/min 1
• The American College of Cardiology recommends avoiding diuretics for volume management in patients with severe renal impairment 4

Why NOT the Other Medications

Carvedilol - Continue

• Beta-blockers are recommended for hypertension management and have cardiovascular protective effects 3
• Carvedilol does not directly cause AKI and should be continued for blood pressure control 3

Atorvastatin - Continue

• Statins do not cause acute kidney injury in this clinical context 5
• While atorvastatin can rarely cause rhabdomyolysis (especially with amlodipine), this patient has no muscle pain or symptoms suggesting rhabdomyolysis 5
• Continue for cardiovascular risk reduction 3

Duloxetine - Continue

• Duloxetine does not cause acute kidney injury 2
• While it can cause nausea (which this patient has), discontinuing it would not address the renal dysfunction 2
• The nausea is more likely uremia-related given the elevated BUN 2

Oxycodone - Continue (with caution)

• Opioids do not directly cause acute kidney injury 2
• However, monitor for potential NSAID co-administration which would worsen nephrotoxicity 1

Immediate Management Algorithm

1. Discontinue hydrochlorothiazide immediately 1
2. Assess volume status clinically (orthostatic vital signs, mucous membranes, skin turgor) 1
3. Initiate IV fluid resuscitation with normal saline if volume depleted 1
4. Check basic metabolic panel within 2-4 weeks after discontinuation to monitor renal recovery 3, 1
5. If blood pressure remains uncontrolled after renal recovery, consider switching to a loop diuretic (furosemide, torsemide, or bumetanide) rather than restarting thiazide 3, 4
6. Alternatively, add an ACE inhibitor or ARB for blood pressure control once renal function stabilizes 3

Critical Pitfalls to Avoid

• Do not assume dose adjustment will make hydrochlorothiazide effective in severe renal impairment - it simply doesn't work at this GFR level 1
• Do not restart hydrochlorothiazide if GFR remains <30 mL/min after recovery 1
• Do not overlook drug interactions - assess for NSAID use which substantially increases risk when combined with thiazides 1
• Do not continue thiazide therapy during intercurrent illness as it can precipitate acute kidney injury 1