How to manage a patient with declining renal function on testosterone therapy?

Management of Declining Renal Function in a Patient on Testosterone Therapy

A patient with declining renal function on testosterone therapy should temporarily discontinue testosterone, undergo comprehensive evaluation for causes of kidney dysfunction, and implement renoprotective strategies including ACE inhibitor or ARB therapy.

Assessment of Renal Function Decline

The patient presents with concerning renal function parameters:

• eGFR decline from 99 to 68 mL/min/1.73m² over the past year
• Current BUN of 26 mg/dL
• Current creatinine of 1.3 mg/dL
• No proteinuria detected

This represents Stage 2 CKD based on the current eGFR of 68 mL/min/1.73m², with an abnormally rapid decline compared to the expected 1% per year age-related decline 1.

Immediate Management Steps

1. Temporarily discontinue testosterone therapy

   • Testosterone may be contributing to the accelerated decline in renal function
   • Reassess renal function after 4-8 weeks off testosterone

2. Comprehensive evaluation for causes of kidney dysfunction

   • Complete urinalysis with microscopy to assess for hematuria, proteinuria, or cellular casts
   • Urine protein-to-creatinine ratio to quantify any protein excretion
   • Renal ultrasound to evaluate kidney structure and rule out obstruction
   • Review of all medications for potential nephrotoxins (especially NSAIDs)
   • Assessment of cardiovascular risk factors (hypertension, diabetes, dyslipidemia)

3. Implement renoprotective strategies

   • Initiate ACE inhibitor or ARB therapy, especially if hypertension is present 1
   • Target blood pressure <130/80 mmHg 1
   • Restrict dietary sodium to <2.0 g/day 1
   • Counsel on "sick day rules" - temporarily holding ACE inhibitors/ARBs during acute illness with volume depletion 1

Monitoring Plan

• Check serum creatinine, BUN, and eGFR every 1-3 months 1
• Monitor serum potassium within 7-14 days after initiation of ACE inhibitor or ARB therapy 1
• Assess for anemia with hemoglobin check every 3 months 1
• Evaluate for other CKD complications including metabolic acidosis, electrolyte abnormalities, and bone mineral disorders 1

Addressing Testosterone Therapy

After initial evaluation and stabilization of kidney function:

1. If renal function improves after testosterone discontinuation:

   • Consider permanent discontinuation or alternative treatments for hypogonadism
   • If testosterone must be resumed, use lowest effective dose with close monitoring of renal function

2. If renal function remains stable or continues to decline:

   • Further nephrology evaluation is warranted
   • Consider renal biopsy if no clear etiology is identified
   • Manage according to standard CKD protocols based on stage and progression

Nephrology Referral

Refer to nephrology if:

• eGFR continues to decline despite interventions
• Proteinuria develops
• Hematuria is detected
• Difficult-to-control hypertension develops
• Other complications of CKD emerge

Lifestyle Modifications

• Advise smoking cessation if applicable 1
• Recommend dietary protein intake of 0.8 g/kg body weight per day 1
• Encourage regular physical activity and weight management if overweight 1
• Consider Mediterranean or DASH eating pattern 1

Medication Adjustments

• Avoid nephrotoxic medications, particularly NSAIDs 1
• Use acetaminophen as first-line therapy for pain management 1
• Adjust medication dosages based on current eGFR for renally excreted drugs 1
• Consider SGLT2 inhibitors if diabetes is present (if eGFR ≥20 mL/min/1.73m²) 1

The rapid decline in renal function over one year is concerning and requires prompt attention to identify and address underlying causes, with particular focus on the potential contribution of testosterone therapy to this decline.