What is the medical name and code for anemia related to severe Chronic Kidney Disease (CKD)?

Anemia of Chronic Kidney Disease: Medical Name and Coding

The medical name for anemia related to severe chronic kidney disease is "Anemia in Chronic Kidney Disease" or "Anemia of CKD," coded as D63.1 (Anemia in chronic kidney disease).

Pathophysiology and Definition

Anemia in CKD is primarily characterized as a normocytic, normochromic anemia that develops as kidney function deteriorates 1. The prevalence increases as glomerular filtration rate (GFR) declines, becoming particularly common when GFR falls below 30 mL/min/1.73m² 1.

The primary cause is insufficient erythropoietin (EPO) production by the diseased kidneys 1. However, multiple mechanisms contribute to this condition:

• Decreased endogenous erythropoietin production
• Absolute and/or functional iron deficiency
• Inflammation with increased hepcidin levels
• Shortened red blood cell survival
• Uremic toxin accumulation

Diagnostic Criteria

Anemia in CKD is defined based on gender-specific hemoglobin values below the 5th percentile for adults over 18 years 1:

• Adult males: Hemoglobin < 13.5 g/dL
• Adult females: Hemoglobin < 12.0 g/dL

Hemoglobin is preferred over hematocrit for diagnosis because:

• More reproducible across laboratories
• Lower within-assessment and between-assessment coefficients of variation
• Not affected by storage time or patient-specific variables like serum glucose 1

Diagnostic Workup

Initial evaluation should include:

1. Complete blood count (CBC) to assess all blood cell lines
2. Iron studies:
   • Serum ferritin (tissue iron stores marker)
   • Transferrin saturation (iron available for erythropoiesis)
   • Note: Interpretation differs in CKD patients 1
     • Absolute iron deficiency in CKD: transferrin saturation ≤20% with ferritin ≤100 μg/L (predialysis/peritoneal dialysis) or ≤200 μg/L (hemodialysis)
     • Functional iron deficiency: transferrin saturation ≤20% with elevated ferritin
3. Reticulocyte count to evaluate bone marrow response
4. Assessment of kidney function (GFR, creatinine)

Clinical Significance

Untreated anemia of CKD is associated with significant physiologic abnormalities 1:

• Decreased tissue oxygen delivery and utilization
• Increased cardiac output and ventricular hypertrophy
• Angina and congestive heart failure
• Decreased cognition and mental acuity
• Impaired immune responsiveness
• Decreased quality of life
• Increased mortality risk

Management Considerations

Treatment typically involves:

1. Iron supplementation (oral or intravenous) to ensure adequate iron stores
2. Erythropoiesis-stimulating agents (ESAs) to address erythropoietin deficiency
3. Monitoring for complications of therapy:
   • Hypertension (most common side effect, occurring in ~23% of treated patients) 2
   • Thrombotic events
   • Pure red cell aplasia (rare but serious)

Important Clinical Pitfalls

1. Misdiagnosis: Not all anemia in CKD patients is due to CKD itself. Other causes should be excluded 1.

2. Iron status misinterpretation: Standard cutoffs for iron deficiency don't apply to CKD patients 1.

3. Overlooking GI bleeding: In non-dialysis CKD patients with iron deficiency not on ESAs and without obvious blood loss, gastrointestinal bleeding should be carefully assessed 1.

4. Treatment complications: Overly aggressive ESA therapy targeting higher hemoglobin levels has been associated with adverse cardiovascular outcomes 3.

5. ESA resistance: Some patients develop resistance to ESAs, requiring alternative management strategies 4.

Regular monitoring of hemoglobin levels is recommended at least yearly in all CKD patients, with more frequent monitoring in diabetic patients who tend to develop anemia at earlier CKD stages 1.