# Clinical Cases: Chronic Kidney Disease

## Case 1: Diabetic Nephropathy with Advanced CKD

### Patient Presentation
**Demographics:** 62-year-old male

**Chief Complaint:** Progressive fatigue and decreased appetite for 3 months

**History of Present Illness:**
The patient has a 20-year history of type 2 diabetes mellitus with poor glycemic control. He reports increasing fatigue, loss of appetite, mild nausea, and restless legs at night. He has noticed decreased urine output and mild bilateral lower extremity swelling. He denies gross hematuria or dysuria.

**Past Medical History:**
- Type 2 diabetes mellitus (HbA1c 9.2%)
- Hypertension (poorly controlled)
- Diabetic retinopathy
- Hyperlipidemia

**Medications:**
- Metformin 1000 mg twice daily
- Lisinopril 20 mg daily
- Amlodipine 10 mg daily
- Atorvastatin 40 mg daily

**Physical Examination:**
- Blood pressure: 158/94 mmHg
- Heart rate: 78 bpm
- General: Pale, appears fatigued
- Cardiovascular: S4 gallop, no murmurs
- Lungs: Clear to auscultation
- Abdomen: Soft, non-tender
- Extremities: 2+ pitting edema bilaterally
- Skin: Dry with mild excoriations from scratching

### Workup and Results

**Laboratory Studies:**
- Creatinine: 3.8 mg/dL (baseline 1.4 mg/dL 2 years ago)
- BUN: 62 mg/dL
- eGFR: 14 mL/min/1.73m2
- Potassium: 5.6 mEq/L
- Bicarbonate: 18 mEq/L
- Phosphorus: 6.2 mg/dL
- Calcium: 8.2 mg/dL
- PTH: 285 pg/mL (elevated)
- Hemoglobin: 9.4 g/dL
- Albumin: 3.0 g/dL
- Urinalysis: 3+ protein, no blood
- Urine albumin-to-creatinine ratio: 2,400 mg/g

**Renal Ultrasound:**
- Bilateral kidneys 9.5 cm with increased echogenicity
- No hydronephrosis or masses

### Clinical Image

![CKD Kidney Ultrasound](case_01_image.jpg)

*Renal ultrasound demonstrating bilateral small, echogenic kidneys consistent with chronic kidney disease. The increased echogenicity reflects parenchymal fibrosis.*

### Diagnosis
**Stage G5 Chronic Kidney Disease (ESKD) due to Diabetic Nephropathy with CKD-Mineral Bone Disorder and Anemia of CKD**

- KDIGO Stage G5 (GFR <15 mL/min/1.73m2)
- Albuminuria Category A3 (>300 mg/g)
- CKD-MBD: Elevated PTH, hyperphosphatemia, hypocalcemia
- Anemia of CKD

### Discussion
This case illustrates advanced diabetic nephropathy:

- **Leading Cause of CKD**: Diabetes mellitus accounts for 40-50% of CKD cases, as noted in the lecture. This patient has classic findings including heavy proteinuria, concurrent diabetic retinopathy, and gradually declining function over years.

- **CKD Staging**: Using KDIGO criteria, the patient has G5 disease (GFR <15) with A3 albuminuria (>300 mg/g). This combination places him at very high risk for progression and cardiovascular mortality.

- **CKD-MBD Pathophysiology**: The lecture describes how declining GFR leads to phosphate retention, decreased 1-alpha hydroxylase activity (low calcitriol), and secondary hyperparathyroidism. FGF-23 rises early as a compensatory phosphaturic hormone.

- **Anemia**: Decreased erythropoietin production from damaged kidneys is the primary mechanism. Target hemoglobin with ESA therapy is 10-11.5 g/dL.

- **Uremic Symptoms**: Fatigue, anorexia, nausea, restless legs, and pruritus represent uremic manifestations as toxins accumulate.

### Treatment Plan
1. **Medication Adjustments:**
   - Discontinue metformin (contraindicated below GFR 30)
   - Continue lisinopril for renoprotection (monitor potassium closely)
   - Add SGLT2 inhibitor if tolerated

2. **CKD-MBD Management:**
   - Dietary phosphorus restriction (<800 mg/day)
   - Sevelamer (non-calcium phosphate binder) with meals
   - Calcitriol 0.25 mcg daily once phosphorus controlled

3. **Anemia Management:**
   - Iron studies to ensure adequate stores (ferritin >100, TSAT >20%)
   - Erythropoietin-stimulating agent (ESA) initiation

4. **Metabolic Acidosis:**
   - Sodium bicarbonate supplementation (bicarbonate <22 mEq/L)

5. **ESKD Preparation:**
   - Nephrology referral for dialysis education (GFR <30)
   - Arteriovenous fistula creation (should occur 6 months before anticipated dialysis)
   - Transplant evaluation referral

### Teaching Points
1. Diabetes is the leading cause of CKD in developed countries
2. KDIGO staging uses both GFR and albuminuria to stratify risk
3. CKD-MBD involves phosphate retention, vitamin D deficiency, and secondary hyperparathyroidism
4. Cardiovascular disease is the leading cause of death in CKD patients
5. RAAS blockade and SGLT2 inhibitors provide renoprotection independent of diabetes status

---

## Case 2: CKD with Medication-Related Complications

### Patient Presentation
**Demographics:** 71-year-old female

**Chief Complaint:** Confusion and weakness for 2 days

**History of Present Illness:**
The patient's daughter brings her to the emergency department because she has been increasingly confused and weak. She has known CKD stage 4 and was recently started on spironolactone for resistant hypertension. She also started taking ibuprofen for knee pain one week ago.

**Past Medical History:**
- CKD stage 4 (baseline creatinine 2.8 mg/dL)
- Hypertensive nephrosclerosis
- Heart failure with preserved ejection fraction
- Osteoarthritis

**Medications:**
- Lisinopril 40 mg daily
- Furosemide 40 mg twice daily
- Spironolactone 25 mg daily (started 2 weeks ago)
- Ibuprofen 600 mg three times daily (started 1 week ago)
- Amlodipine 10 mg daily

**Physical Examination:**
- Blood pressure: 102/58 mmHg (baseline 140/80)
- Heart rate: 52 bpm
- General: Lethargic, confused
- Cardiovascular: Bradycardic, irregular rhythm
- Lungs: Clear
- Extremities: No edema

### Workup and Results

**Laboratory Studies:**
- Creatinine: 5.2 mg/dL (baseline 2.8)
- BUN: 78 mg/dL
- Potassium: 7.4 mEq/L
- Sodium: 128 mEq/L
- Bicarbonate: 16 mEq/L

**ECG:**
- Peaked T waves
- Widened QRS complex
- Heart rate 48 bpm

### Clinical Image

![Hyperkalemia ECG](case_01_image.jpg)

*Electrocardiogram demonstrating classic findings of severe hyperkalemia: peaked T waves, prolonged PR interval, and widened QRS complex.*

### Diagnosis
**Acute-on-Chronic Kidney Injury with Severe Hyperkalemia**

Contributing factors:
- NSAID use (ibuprofen) reducing renal perfusion
- Triple whammy: ACE inhibitor + diuretic + NSAID
- Spironolactone potentiating hyperkalemia

### Discussion
This case demonstrates medication-related AKI superimposed on CKD:

- **Triple Whammy Effect**: The lecture describes how the combination of ACE inhibitors, diuretics, and NSAIDs creates a "perfect storm" for AKI. NSAIDs block prostaglandin-mediated afferent arteriolar dilation while ACE inhibitors prevent efferent arteriolar constriction, dramatically reducing GFR.

- **Hyperkalemia Mechanisms**: Multiple factors contributed: NSAID-induced AKI reducing potassium excretion, spironolactone blocking ENaC-mediated potassium secretion, and ACE inhibitor reducing aldosterone. The lecture notes that potassium-sparing diuretics require careful monitoring in CKD.

- **Life-Threatening Emergency**: Potassium above 7.0 mEq/L with ECG changes requires emergent treatment. The wide QRS and peaked T waves indicate cardiac membrane instability.

### Treatment Plan
1. **Emergent Hyperkalemia Management:**
   - IV calcium gluconate (cardiac membrane stabilization)
   - IV insulin with glucose (shift potassium intracellularly)
   - Sodium bicarbonate (if acidotic)
   - Kayexalate or patiromer (potassium removal)
   - Prepare for emergent hemodialysis if refractory

2. **Medication Discontinuation:**
   - Stop ibuprofen immediately
   - Hold spironolactone
   - Hold lisinopril temporarily

3. **Volume Resuscitation:**
   - Careful IV fluids (patient has heart failure history)

4. **Long-term Management:**
   - Acetaminophen for pain (avoid NSAIDs in CKD)
   - Reassess need for spironolactone
   - Restart ACE inhibitor at lower dose once stable

### Teaching Points
1. NSAIDs should be avoided in CKD due to hemodynamic effects and AKI risk
2. The "triple whammy" combination greatly increases AKI risk
3. Hyperkalemia is a medical emergency requiring immediate ECG assessment
4. Acceptable creatinine rise after ACE inhibitor initiation is up to 30%
5. Drug dosing must be adjusted for reduced GFR

---

## Image Reference

For visual reference of CKD concepts, see:
- Radiopaedia: [Chronic kidney disease](https://radiopaedia.org/articles/chronic-kidney-disease) - Imaging findings
- Wikimedia Commons: [Kidney ultrasound](https://commons.wikimedia.org/wiki/Category:Kidney_ultrasound) - Normal and pathologic appearances
- Radiopaedia: [Hyperkalemia ECG changes](https://radiopaedia.org/articles/hyperkalaemia) - Cardiac manifestations

---

## Learning Points

1. **CKD Definition**: Kidney damage or GFR <60 mL/min/1.73m2 persisting for at least 3 months

2. **Diabetes is #1 Cause**: Diabetes mellitus accounts for 40-50% of CKD cases; control proteinuria with RAAS blockade

3. **CKD-MBD Triad**: Hyperphosphatemia, hypocalcemia, and secondary hyperparathyroidism require dietary restriction and phosphate binders

4. **Anemia Target**: Hemoglobin 10-11.5 g/dL with ESAs; ensure iron repletion first (ferritin >100, TSAT >20%)

5. **Avoid Nephrotoxins**: NSAIDs, aminoglycosides, and iodinated contrast require extreme caution or avoidance in CKD