What is the most likely diagnosis and recommended management for a patient presenting with new‑onset leg weakness, chronic kidney disease with impaired renal function (elevated creatinine, reduced eGFR, elevated BUN), anemia of chronic disease, and mild leukocyte abnormalities (elevated immature granulocytes and basophilia)?

New-Onset Leg Weakness with Stage 3B CKD and Anemia

This patient requires urgent neurological evaluation for the leg weakness while simultaneously addressing anemia of chronic kidney disease (CKD) with iron deficiency, which is contributing to decreased tissue oxygen delivery and potentially worsening neurological symptoms.

Most Likely Diagnosis

The clinical picture suggests two concurrent processes:

1. Anemia of CKD with iron deficiency (Hgb 9.6 g/dL, eGFR 36 mL/min/1.73m²)
2. Acute neurological process requiring urgent investigation (new-onset leg weakness is NOT a typical presentation of anemia alone)

The anemia is consistent with CKD Stage 3B, where anemia prevalence increases significantly when eGFR falls below 60 mL/min/1.73m² 1. The leg weakness, however, demands immediate neurological workup as it suggests spinal cord compression, peripheral neuropathy, or other neurological emergency that could result in permanent disability if not addressed urgently.

Critical Immediate Actions

1. Neurological Emergency Evaluation

• Obtain urgent MRI of spine to rule out spinal cord compression, epidural abscess, or transverse myelitis
• Assess for uremic neuropathy (though less likely at this eGFR level)
• Check for Guillain-Barré syndrome or other acute inflammatory demyelinating polyneuropathy
• Evaluate for multiple myeloma given the combination of renal dysfunction, anemia, and potential neurological involvement 2

2. Complete Anemia Workup

Per NKF-K/DOQI guidelines 3, evaluate:

• Iron studies: Serum ferritin and transferrin saturation (TSAT)
  • In CKD, absolute iron deficiency is defined as TSAT ≤20% with ferritin ≤100 μg/L 1
• Reticulocyte count (assess bone marrow response)
• Vitamin B12 and folate levels (rule out additional nutritional deficiencies)
• Thyroid function tests (hypothyroidism causes normocytic anemia mimicking EPO deficiency) 3
• Serum protein electrophoresis and free light chains (rule out multiple myeloma given renal dysfunction and anemia) 2

The mild basophilia (0.1) and immature granulocytes (0.5) warrant consideration of myelodysplastic syndrome or plasma cell dyscrasia, especially with concurrent renal dysfunction 4, 2.

Management Algorithm

Step 1: Address Iron Deficiency (First-Line)

Iron replacement should be initiated before or concurrent with erythropoiesis-stimulating agents (ESAs) 3:

• If TSAT ≤20% and ferritin ≤100 μg/L: Start iron supplementation
  • Oral iron: First-line for non-dialysis CKD patients if tolerated 1
  • Intravenous iron: If oral iron not tolerated, ineffective, or rapid correction needed 1
  • Typical regimen: 200 mg IV weekly for 3 weeks, then reassess 4

Step 2: Consider ESA Therapy

Target hemoglobin: 100-120 g/L (10-12 g/dL) per current evidence 5, 6, 7, 8:

• Do NOT target hemoglobin >130 g/L - associated with increased cardiovascular events and mortality without quality of life benefit 5
• Initiate ESA if:
  • Hemoglobin remains <100 g/L despite iron repletion
  • Symptomatic anemia affecting quality of life
  • Iron stores adequate (ferritin >100 μg/L, TSAT >20%)

ESA options (no dose adjustment needed for renal function) 2:

• Epoetin alfa (Epogen/Procrit)
• Darbepoetin alfa
• Consider newer HIF-prolyl hydroxylase inhibitors per 2026 KDIGO guidelines, though ESAs remain preferred first-line 7, 8

Step 3: Monitor and Adjust

• Recheck CBC, iron studies in 2 months after initiating iron therapy 4
• Monitor for ESA hyporesponsiveness: If inadequate response despite adequate dosing, investigate:
  • Ongoing blood loss
  • Severe hyperparathyroidism
  • Chronic inflammation
  • Aluminum toxicity
  • Myelodysplastic syndrome 3, 4

Critical Pitfalls to Avoid

1. Do NOT attribute leg weakness solely to anemia - this hemoglobin level (9.6 g/dL) does not cause acute motor weakness. Neurological evaluation is mandatory.

2. Do NOT target "normal" hemoglobin levels - multiple trials demonstrate harm with hemoglobin >130 g/L, including increased cardiovascular events and death 5, 6

3. Do NOT start ESA without assessing iron stores - functional iron deficiency will render ESA therapy ineffective 3

4. Do NOT overlook multiple myeloma - the combination of renal dysfunction (creatinine 1.92, eGFR 36), anemia, and neurological symptoms should prompt serum/urine protein electrophoresis and free light chains 2

5. Monitor potassium and phosphate in CKD Stage 3B - these patients require screening for CKD complications including metabolic bone disease and electrolyte abnormalities 9

Specific Considerations for This Patient

The elevated BUN:creatinine ratio (24:1.92 = 12.5:1) suggests possible:

• Volume depletion
• GI bleeding (contributing to anemia)
• High protein intake
• Catabolic state

Investigate for occult GI blood loss given iron deficiency anemia in CKD - most CKD patients with confirmed iron deficiency anemia warrant GI evaluation 1.

The combination of renal dysfunction, anemia, and neurological symptoms mandates ruling out plasma cell dyscrasia (multiple myeloma, light chain deposition disease) which can present with all three features 2.