# Geriatric Nephrology

## 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 per the 2025 AHA/ACC guideline and the ADA Standards of Care. **KDIGO 2021** (Blood Pressure in CKD) suggests a systolic target \<120 mmHg when tolerated, using standardized office measurement (grade 2B, driven by the CKD subgroup of SPRINT); it explicitly excludes kidney transplant recipients and patients on dialysis. Much of the gap is measurement technique rather than disagreement about physiology — KDIGO's lower number presumes a standardized or unattended reading, which most routine clinic cuffs do not meet.
- **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

1.  **What is most important?** (Quality of life, length of life, time at home, minimizing burden)
2.  **What are realistic expectations?** (Dialysis improves survival but doesn’t “cure” CKD; life expectancy \<5 years common)
3.  **Can patient handle regimen?** (Physical, cognitive, transportation, social support)
4.  **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

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

## References

1.  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](https://pubmed.ncbi.nlm.nih.gov/17855638/)
2.  Kidney Disease: Improving Global Outcomes (KDIGO) Blood Pressure Work Group. KDIGO 2021 Clinical Practice Guideline for the Management of Blood Pressure in Chronic Kidney Disease. *Kidney Int* 2021. [PubMed 33637192](https://pubmed.ncbi.nlm.nih.gov/33637192/).
3.  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](https://pubmed.ncbi.nlm.nih.gov/19828531/)
4.  Wong SP, Kreuter W, O'Hare AM. Healthcare intensity at initiation of chronic dialysis among older adults. *J Am Soc Nephrol* 2014. [PubMed 24262795](https://pubmed.ncbi.nlm.nih.gov/24262795/).
5.  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](https://pubmed.ncbi.nlm.nih.gov/11253156/)
6.  Davison SN. Advance care planning in patients with chronic kidney disease. *Semin Dial*. 2012;25(6):657-663. [DOI](https://doi.org/10.1111/sdi.12039) \| [PubMed](https://pubmed.ncbi.nlm.nih.gov/23173893/)
7.  Murtagh FEM, Burns A, Moranne O, et al. Supportive Care: Comprehensive Conservative Care in End-Stage Kidney Disease. *Clin J Am Soc Nephrol* 2016. [PubMed 27510453](https://pubmed.ncbi.nlm.nih.gov/27510453/).
8.  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](https://pubmed.ncbi.nlm.nih.gov/22699366/)


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