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Living Donor Risks Living Kidney Donor

Anemia and Kidney Function

A living kidney donor recently asked me if there was a connection between kidney donation and anemia. Because I’m not a walking encyclopedia, I put my google-fu to work and learned a lot along the way.

An analysis of NHANES III found that a GFR <60 was associated with a lower hemoglobin level and a higher prevalence of anemia.

(Note:Hemoglobin is the part of the red blood cell that carries iron and helps transport oxygen throughout the body.)

“The prevalence of anemia was 1.8% among those with an estimated GFR of 90 or higher, compared with 5.2% among those with an estimated GFR between 30 and 59, and 44.1% among those with an estimated GFR between 15 and 29.”

“Non-Hispanic black persons had a lower mean hemoglobin level than non-Hispanic white persons. Older age, female sex, and elevated CRP [C-reactive protein] level were also significantly associated with lower hemoglobin levels.”

This article has multiple tables and figures; go check them out.

 

A study of 5222 folks diagnosed with chronic kidney disease but not yet on dialysis (meaning they have not yet progressed to end-stage renal disease) found a higher prevalence of anemia as GFR declines.

“Percentage of patients with hemoglobin less than or equal to 12 g/dL [the cut-off for an anemia diagnosis] increased from 26.7% to 75.5% when glomerular filtration rate decreased from greater than or equal to 60 to < 15.”

“Prevalence of hemoglobin less than or equal to 10 g/dL increased substantially from 5.2% to 27.2% when glomerular filtration rate diminished from 60 to < 15.”

“Anemia was present in 47.7% of 5222 predialysis patients with chronic kidney disease”

 

Nurko states that most people “with chronic kidney disease eventually become anemic”.

“Factors likely contributing to anemia in chronic kidney disease include blood loss, shortened red cell life span, vitamin deficiencies, the “uremic milieu,” erythropoietin (EPO) deficiency, iron deficiency, and inflammation.”

“Deficiency of erythropoietin is the primary cause of anemia in chronic renal failure, but it is not the only cause. A minimal workup is necessary to rule out iron deficiency and other cell-line abnormalities.”

Erythropoietin is a protein excreted by the kidneys (yet another thing potential living kidney donors aren’t told prior to donating) which promotes the formation of red blood cells by the bone marrow. The kidney cells responsible for making erythropoietin are sensitive to oxygen levels in the blood, releasing erythropoietin when they drop too low. Red blood cells, as well, carry oxygen.

“Researchers postulate that the specialized peritubular cells that produce EPO are partially or completely depleted or injured as renal disease progresses, so that EPO production is inappropriately low relative to the degree of anemia”

 

“The consensus is that untreated anemia contributes to the large cardiovascular disease burden in [the CKD} population.”

“Left ventricular hypertrophy is closely linked to chronic kidney disease. The estimated prevalence in stage 3 and 4 is 39%, and it is even higher in patients with lower renal function”

If iron supplements don’t correct the issue, this author recommends the addition of an erythropoiesis-stimulating agent (ESA). “Studies suggest that treating anemia with a goal of raising the hematocrit to at least 36% improves quality of life, decreases the need for transfusions, improves muscle strength and cognitive function, and decreases rates of hospitalization and death”

Take care of yourself!

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Living Donor Risks

Low Kidney Function Associated With Cognitive Impairment

“Chronic kidney disease (CKD) has a well-established association with impairment on neurocognitive tests, particularly measures of frontal/executive function”

“MCI [Mild Cognitive Impairment] is a transitional state between normative cognitive aging and dementia. MCI is  often divided into amnestic (aMCI) form, with reduced memory performance and nonamnestic forms (naMCI), with reduced performance in cognitive domains other than memory”

I bolded the phrase because the study subjects were 70 years old and above. It’s easy to think “Eh, old people are all batty” but this study is specifically looking at cognitive impairment beyond that of normal aging. Besides, we living kidney donors hope to make to 70, right?

 

“The estimated glomerular filtration rate (eGFR, calculated in mL/min/1.73 m2 units) was classified into low (<45), moderate (45–59), and high (>60).”

Conclusion:

“Low eGFR was independently associated with dMCI and aMCI in fully adjusted models.”

“At cross-section low eGFR is associated with a higher risk of both dMCI and aMCI. eGFR may contribute to the development of these cognitive states directly. Alternatively, low eGFR may be a marker for risk factors that influence both the kidney and the brain, such as coronary microvascular disease.”

 

Full study available here: http://www.sciencedirect.com/science/article/pii/S2352872915000330

 
Zammit, A., Katz, M., Zimmerman, M., Bitzer, M., & Lipton, R. (2015). Low eGFR is associated with dysexecutive and amnestic mild cognitive impairment Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring DOI: 10.1016/j.dadm.2014.12.002

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Living Donor Research Living Kidney Donor

Post-Operative Kidney Function in Living Kidney Donors vs. Renal Cell Cancer

The authors compared 94 pairs of living kidney donors and folks who underwent nephrectomy due a cancerous kidney tumor.

Median pre-nephrectomy GFR was nearly equal for both groups.

But:

 

In living kidney donors, median eGFR decreased by 34.4 % immediately after surgery. Compared with matched RN-patients, immediate postoperative [kidney function] is significantly more pronounced.

 

And:

The percentage decrease in living kidney donors was higher than the comparison group too.

 

Why? They don’t know for sure, but one theory is that the folks with renal cancer were already exhibiting signs of hyperfiltration prior to surgery.

 
Vergho, D., Burger, M., Schrammel, M., Brookman-May, S., Gierth, M., Hoschke, B., Lopau, K., Gilfrich, C., Riedmiller, H., Wolff, I., & May, M. (2014). Matched-pair analysis of renal function in the immediate postoperative period: a comparison of living kidney donors versus patients nephrectomized for renal cell cancer World Journal of Urology DOI: 10.1007/s00345-014-1423-1

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Living Donor Risks

Losing a Whole Kidney vs. Part of One Matters

I’ll let the authors begin:

 

 It is clear  that Chronic Kidney Disease  (GFR <60mls/min) is associated with reduced  life  expectancy,  partly  due  to  an  increased  risk  of  cardiovascular  disease.

 

Are we clear? Reduced kidney function = increased risk of cardiovascular disease. Try to remember that when a member of the transplant industry tries to say that living kidney donors have no increased risk of heart disease.

 

Anyway, so these authors compared two groups: those who had a whole kidney removed, and those who only had part of a kidney removed.

 

16.7& of those who had a partial nephrectomy had a post-surgical GFR <60.

35.4% of the full nephrectomy group had GFR of <60.

Six months post-nephrectomy. (PS. GFR <60 is considered Stage 3 Chronic Kidney Disease.)

 

Their conclusion:

 

Smaller  reductions  of  GFR  after  partial  versus  total  unilateral nephrectomy  are  of  magnitudes  that  are  significant  for  overall  life  expectancy  in  large  cohorts

 

 

Stephen  KD  Hamilton , Grant  D  Stewart , Alan  McNeill , Antony CP  Riddick   , & Richard  Phelps  (2014). Renal Function After Unilateral Nephrectomy
Scottish Universities Medical Journal  , 3 (2), 22-31

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Living Donor Research Living Donor Risks Living Kidney Donor

Hyperfiltration Post-Donation Associated With Body Size

74 living kidney donors had their single kidney function (SK-GFR) measured before donation (mean=54.2-54.6), and the remaining kidney post-donation [note: abstract doesn’t say when, post-donation].

Sk-GFR of remaining kidney showed significantly hyperfiltration by 33.6 % after kidney donation.

The the researchers divided the LKDs into three groups: low SK-GFR, meaning those whose SK-GFR didn’t change much pre to post-donation; moderate SK-GFR; high SK-GFR.
 
Conclusion: In most patients, sk-GFR of remaining kidney showed significant increase due to adaptive hyperfiltration, however in patients with large body size and high sk-GFR of remaining kidney, the adaptive hyperfiltration was insignificant.

 
This means that for a person with ‘large body size’, their kidneys may already be hyperfiltrating prior to donation, leading to little, if any, regaining of renal function in the year or so after nephrectomy. This analysis sheds light on an added risk factor for heavier/larger potential living donors.

 
 
Full Abstract: http://www.atcmeetingabstracts.com/abstract/change-of-single-kidney-glomerular-filtration-rate-in-kidney-donors-after-kidney-donation-the/