Geriatric Nephrology - Urine Nephrology Now

Andrew Bland, MD, MBA, MS

Aging & Renal Physiology

Age-Related GFR Decline

GFR declines ~1 mL/min/1.73m²/year after age 40 (average)
NOT linear: Variable among individuals (some stable, others steeper decline)
By age 80: Mean GFR ~60 mL/min/1.73m² in absence of kidney disease

Clinical Pearl: Serum Creatinine Paradox

Serum creatinine may remain “normal” (<1.0 mg/dL) despite significant GFR decline. Mechanism: Decreased muscle mass + decreased creatinine production in elderly → lower baseline creatinine. Always calculate eGFR (CKD-EPI) in all elderly patients; never rely on creatinine alone.

Structural Changes

Progressive renal atrophy with age (1–2% per decade after age 40)
Glomerular sclerosis progresses (10–15% sclerotic glomeruli by age 80 in absence of disease)
Glomerular basement membrane thickening; vascular sclerosis limiting renal perfusion

Functional Impairments

Function	Change	Clinical Implication
Concentrating ability	Max urine osm 800 vs 1200+ in young	Risk of dehydration-induced AKI
Acid-base regulation	Reduced urine acidification; decreased NH3 excretion	RTA risk; higher serum K+ at given GFR
Thirst mechanism	Impaired thirst response	Dehydration risk
ADH sensitivity	Increased sensitivity	Hyponatremia risk with diuretics
Drug clearance	Many drugs renally cleared; accumulation with CKD	Polypharmacy risk (median 5–10 medications)

Epidemiology of CKD in Elderly

Prevalence: 30–50% of adults >70 years have eGFR <60
ESRD: Fastest-growing segment is elderly (age >75 on dialysis growing)
Comorbidities: Hypertension (80%), diabetes (40%), cardiovascular disease (50%+)
CKD progression: Slower than younger populations; variable trajectory

Causes of CKD in Elderly

Most Common

Diabetic nephropathy: Most common cause of ESRD in elderly (25–30%); often decades of type 2 diabetes
Hypertensive nephrosclerosis: Second most common (20–25%); often multifactorial
Recurrent AKI: Baseline CKD + acute insult → CKD progression. Common precipitants: NSAIDs, ACE-I/ARB initiation, dehydration, sepsis, contrast

Less Common but Important

Renovascular disease (atherosclerotic RAS): 5–10% of elderly CKD; progressive ischemic nephropathy
Urinary obstruction: BPH/prostate cancer in men; malignancy, stricture in either gender
Glomerulonephritis: ANCA vasculitis and anti-GBM disease can present >60 years
Contrast-induced nephropathy: Risk factors include CKD, diabetes, dehydration

Conservative Management (Non-Dialytic CKD Care)

Comprehensive management of CKD without dialysis or transplant. Appropriate for eGFR 10–20 in many elderly patients. Achieves quality of life, slows progression, addresses comorbidities.

1. Blood Pressure Control

Target: <130/80 mmHg (ACC/AHA 2017 for CKD)
Agents: ACE-I/ARB first-line (renal protection) if tolerated
Monitor K+, Cr closely (acute rise may indicate critical stenosis/advanced CKD)
Caution: Aggressive BP lowering may reduce renal perfusion in elderly

2. RAAS Inhibition

Slows CKD progression; reduces albuminuria/proteinuria
Monitoring: K+, Cr 1–2 weeks after initiation, then every 3–6 months
Relative contraindication: Creatinine rise >30%, hyperkalemia K+ >6

3. Mineral-Bone Metabolism

Phosphate binders: Calcium-based vs non-calcium (sevelamer, lanthanum)
Calcium-based binders: Risk of vascular calcification in elderly; consider non-calcium alternatives
Monitor: Calcium, phosphate, PTH, alkaline phosphatase

4. Anemia Management

Ferritin <100 or TSAT <20%: Iron supplementation
ESA: If Hgb <10 in symptomatic elderly; target Hgb 10–11 (conservative)
Avoid transfusion unless Hgb <7 (CV risk)

5. Nutrition & Protein

Protein: 0.6–0.8 g/kg/day; monitor nutrient intake
Phosphate: <1000 mg/day
Potassium: <2000–3000 mg/day if hyperkalemia
Sodium: <2000 mg/day

6. Medication Management

Avoid nephrotoxins: NSAIDs, excess ACE-I/ARB, certain antibiotics
De-prescribe: Regular review for unnecessary medications (polypharmacy risk)

Warning: Triple Whammy

Avoid NSAID + ACE-I/ARB + diuretic simultaneously in elderly patients. This combination carries high AKI risk. Always assess concurrent medications before adding any of these three drug classes.

Dialysis: Indications, Timing, and Modalities

Absolute Indications for Dialysis

Severe uremia (symptoms despite conservative care)
Refractory hyperkalemia (K+ >6.5 despite management)
Refractory fluid overload (pulmonary edema despite diuretics)
Uremic pericarditis

Timing in Elderly

“Planned” start: eGFR 5–10 mL/min/1.73m² allows vascular access placement
“Urgent” start: Acute deterioration; less optimal outcomes
Avoid: Unnecessarily early start (premature frailty) and avoidable late start (acute complications)

Modalities in Elderly

Modality	Advantages	Disadvantages	Best For
In-Center HD (3×/wk)	Predictable, established, frequent monitoring	3 visits/week; vascular access complications; hypotension	Most elderly patients (most common)
Peritoneal Dialysis	Home-based, gentler BP stability, preserves residual renal function	Requires dexterity, peritonitis risk, difficult with dementia	Functional, cognitively intact elderly
Twice-Weekly HD	Fewer sessions; less aggressive; may reduce hospitalization	Emerging evidence; less solute clearance	Frail elderly with residual renal function

Patient Outcomes by Choice

Outcome	Dialysis (Age >75)	Conservative Management
Median survival	3–4 years	1–3 years from eGFR <10
Hospitalization	20–30% annual rate	Lower rates
Quality of life	Variable; many report good satisfaction	Better symptom control in many
Cause of death	Cardiovascular; infection	Comorbidities (not uremia, if managed well)

Shared Decision-Making & Palliative Nephrology

Key Questions for Elderly Patient/Family

What is most important? (Quality of life, length of life, time at home, minimizing burden)
What are realistic expectations? (Dialysis improves survival but doesn’t “cure” CKD; life expectancy <5 years common)
Can patient handle regimen? (Physical, cognitive, transportation, social support)
What would be “unbearable”? (Frequent hospitalizations, major lifestyle change, loss of independence)

Appropriate Scenarios for Non-Dialytic Management

Advanced dementia with ESRD (unable to consent, understand, cooperate)
Severe functional decline (bedridden, multiple comorbidities)
Short life expectancy from non-renal disease (metastatic cancer, end-stage heart/lung disease)
Explicit patient refusal

Goals shift to: symptom relief (uremia, dyspnea, pain), comfort care, advance care planning, palliative care/hospice involvement.

Specific Geriatric Considerations

AKI in Elderly

Increased incidence and slower recovery
Risk factors: Medications, dehydration, contrast, sepsis
Management: Volume assessment critical; often hypovolemic (avoid aggressive diuresis)
Stop NSAIDs, ACE-I/ARB temporarily; monitor closely

Cognitive Impairment & CKD

Uremia may worsen cognition (reversible with dialysis if early)
Distinguish: uremia vs medication effects vs primary dementia
Avoid/minimize: NSAIDs (mental status), benzodiazepines (cognition)

Frailty Assessment

Fried Frailty Phenotype: Unintended weight loss, weakness, exhaustion, slow gait, low activity
High frailty: Consider non-dialytic pathway
Moderate frailty: Shared decision-making
Low frailty: Dialysis reasonable

Medication Dosing

eGFR-based dosing essential (not just creatinine)
Polypharmacy review: Look for duplicates, interactions, unnecessary drugs
Key nephrotoxins to minimize: NSAIDs (even topical + systemic = risk), contrast (limit volume, prehydrate), aminoglycosides

Clinical Pearls

Never rely on serum creatinine alone in elderly—calculate eGFR; low creatinine does not equal preserved renal function
GFR decline variable in elderly—some stable, others progressive; baseline + trajectory matter
Avoid the “triple whammy” (NSAID + ACE-I + diuretic)—high AKI risk in elderly
Creatinine rise after ACE-I/ARB initiation: Consider critical RAS vs advancing CKD; do not reflexively stop
Dialysis survival in elderly <5 years median—realistic expectations essential
Conservative management appropriate for many eGFR 10–20 elderly—reduces burden, maintains quality of life
Dehydration is a major risk in elderly CKD—encourage fluid intake; monitor for hypernatremia
Cognitive impairment may reverse with dialysis if uremia-related but is permanent if dementia
Frailty assessment helps guide dialysis vs conservative pathway
Palliative nephrology for advanced dementia, severe comorbidity, patient choice—good outcomes possible

References

O’Hare AM, Choi AI, Bertenthal D, et al. Age affects outcomes in chronic kidney disease. J Am Soc Nephrol. 2007;18(10):2758-2765. PubMed
Kidney Disease: Improving Global Outcomes (KDIGO). Clinical practice guideline for the management of blood pressure in CKD. Kidney Int Suppl. 2021;11(1):1-104. PubMed
Kurella Tamura M, Covinsky KE, Chertow GM, et al. Functional status of elderly adults before and after initiation of dialysis. N Engl J Med. 2009;361(16):1539-1547. PubMed
Wong SP, Kreuter W, O’Hare AM. Trends in the rates of dialysis and kidney transplantation in older adults. J Am Soc Nephrol. 2016;27(10):2941-2950. PubMed
Fried LP, Tangen CM, Walston J, et al. Frailty in older adults: evidence for a phenotype. J Gerontol A Biol Sci Med Sci. 2001;56(3):M146-M156. PubMed
Davison SN. Palliative care and end-of-life issues in advanced CKD. Semin Dial. 2012;25(6):654-664. PubMed
Murtagh FE, Burns A, Richardson J, et al. The perspectives of patients living with advanced CKD. Nephrol Dial Transplant. 2007;22(8):2134-2142. PubMed
Rosansky SJ. Renal function trajectory is more important than CKD stage for managing patients with CKD. Am J Nephrol. 2012;35(6):557-561. PubMed