What is the target blood pressure for a patient with a solitary kidney and normal renal function, indicated by a creatinine level in the normal range, and current blood pressure of 128/90 mmHg?

Blood Pressure Management in a Patient with Solitary Kidney and Normal Renal Function

For a patient with a solitary kidney and normal renal function (creatinine in the 70s), the target blood pressure should be <140/90 mmHg, with consideration for a more stringent target of <130/80 mmHg if the patient can tolerate it without adverse effects. 1

Rationale for Blood Pressure Target

Current Guideline Recommendations

• Different guidelines provide varying recommendations for blood pressure targets in patients with kidney disease:
  • The American College of Cardiology recommends <130/80 mmHg 1
  • European Society of Cardiology/European Society of Hypertension recommends systolic BP of 130-139 mmHg 2
  • National Institute for Health and Care Excellence (NICE) recommends <140/90 mmHg for CKD with low albuminuria 1
  • KDIGO (2021) recommends systolic BP <120 mmHg, though this is considered an outlier among guidelines 2

Special Considerations for Solitary Kidney

• Patients with a solitary kidney require careful blood pressure management to preserve remaining kidney function
• The current blood pressure of 128/90 mmHg (and home readings in the 120s/high 80s) indicates the diastolic pressure is above optimal targets
• With normal renal function, the primary goal is to prevent progression of kidney disease while minimizing cardiovascular risk

Management Approach

Step 1: Initial Target

• Begin with a target of <140/90 mmHg as a minimum goal 2
• Focus particularly on reducing the diastolic pressure from the current 90 mmHg to <90 mmHg
• Once this is achieved, consider further reduction to <130/80 mmHg if tolerated 1

Step 2: Medication Selection

• First-line therapy should include an ACE inhibitor or ARB, which provides renoprotection 1
• Add a thiazide-type diuretic if needed for additional BP control 2
• If target BP is not achieved with two medications, consider adding a calcium channel blocker as a third agent

Step 3: Monitoring

• Monitor kidney function and electrolytes 1-2 weeks after initiating or adjusting RAAS blockers 1
• Check for orthostatic changes in blood pressure, especially if pursuing more intensive targets
• Assess for symptoms of hypotension if pursuing lower targets
• Monitor for any increase in creatinine (should not exceed 30% from baseline) 1

Important Caveats

Avoiding Overly Aggressive Targets

• While KDIGO recommends a target of <120 mmHg systolic, this recommendation is based primarily on the SPRINT trial and may not be appropriate for all patients with kidney disease 2
• Overly aggressive BP lowering could potentially lead to:
  • Acute kidney injury
  • Electrolyte abnormalities
  • Hypotension, especially in elderly patients 1
  • Excessive lowering of diastolic pressure (should generally not be <70 mmHg) 1

Monitoring Home Blood Pressure

• Since the patient already monitors home blood pressure, encourage continued monitoring
• Home readings in the 120s/high 80s suggest that office readings may be slightly elevated (white coat effect)
• Target home readings of approximately 120-130/70-80 mmHg

Conclusion

For this patient with a solitary kidney, normal renal function, and current BP of 128/90 mmHg, the primary focus should be on reducing the diastolic pressure to <90 mmHg while maintaining the systolic pressure <140 mmHg. A more intensive target of <130/80 mmHg may be appropriate if well-tolerated, but pursuing targets below this level should be approached with caution to avoid adverse effects that could compromise the remaining kidney function.