Anaemia (CKD) Flashcards
What is anaemia?
a condition in which the number of red blood cells or the haemoglobin concentration within them is lower than normal
- Men: Hgb < 13.0 g/dl
- Women: Hbg < 12.0 g/dl
is a frequent complication of chronic kidney disease (CKD)
- renal anaemia is due to low renal blood flow or low EPO
- seen in CKD stage 3b and 4
What are the symptoms of chronic kidney disease?
headaches
muscle cramps - hyperkalaemia, reduced potassium excretion
darkness of skin
itchy skin - excess blood phosphorus
insomnia
dyspnoea
oedema - unable to regulate blood volume
weakness and fatigue - anaemia
nausea
hypertension
erectile dysfunction in men
loss of appetite and weight loss
hematuria
increased frequency of urination
What is chronic kidney disease?
a reduction in kidney function (GFR <60 mL/min/1.73 m2) or structural damage (or both) present for more than 3months, with associated health implications
also known as
- chronic renal insufficiency or failure
How is CKD diagnosed?
markers of kidney damage
- urinary ACR >3mg/mmol
- electrolyte and other abnormalities due to tubular disorders
- urine sediment abnormalities (RBCs, WBCs)
- structural abnormalities detected by imaging
What are CKD associated problems?
urea is not excreted
- azotaemia (build up of nitrogenous products) is toxic
potassium is not excreted
- hyperkalaemia
less activated vitamin D
- less calcium is absorbed from the blood, PTH is release and bones lose calcium
- renal osteodystrophy
increased renin secretion
- hypertension occurs
How does hypertension affect glomeruli?
afferent arteriole is thickened and narrowed by high blood pressure
- less blood flow and oxygen leads to ischaemic injury
macrophage and foam cell infiltration
- secretion of TGF beta
- mesangial cells differentiate and secrete extracellular matrix
- scarring and hardening of glomeruli occurs which reduces filtration, causes loss of nephrons and lowers GFR
How does diabetes affect glomeruli?
non-enzymatic glycation of proteins
- stiffens and narrows arterioles which increases pressure in the glomerulus
hypertrophy
- occurs as mesangial cells secrete more matrix and expand
What are the causes of CKD?
Damaged nephrons cannot filter the blood - reduction in GFR:
1 - damaged quickly by injury or toxins
2 - damaged slowly over time e.g. by hypertension and diabetes.
What is anaemia caused by?
impaired synthesis of erythropoietin (EPO) from renal cortical peritubular interstitial cells
- in CKD, they transdifferentiate into myofibroblast, and subsequently their ability to secrete EPO is decreased
What factors cause anaemia?
erythrocyte loss
- bleeding
decreased erythrocyte production
- low erythropoietin
- decreased marrow response to erythropoietin
increased erythrocyte destruction
- hemolysis
nutritional deficiencies
myelosuppression due to toxins, chemicals or radiation
infection
bone marrow replacement by malignant cells
What are the symptoms of anaemia?
eyes - yellowing
skin - paleness, coldness, yellowing
respiratory - dyspnoea
muscular - weakness
intestinal - changed stool colour
central - fatigue, dizziness, fainting (severe)
blood vessels - low blood pressure
heart - palpitations, rapid heart rate, chest pain/angina/heart attack (severe)
spleen - enlargement
How can anaemia be measured?
Haemoglobin = grams of hemoglobin per 100 mL of whole blood (g/dL)
Hematocrit = percent (%) of a sample of whole blood occupied by intact red blood cells
RBC = millions of red blood cells per microL of whole blood
MCV = Mean corpuscular volume (average size of RBCs)
- if > 100 → Macrocytic anemia
- if 80 – 100 → Normocytic anemia
- if < 80 → Microcytic anemia
RDW = RBC distribution width (differences in the volume and size of RBCs)
- normal value is 11-15%
- if elevated, suggests large variability in sizes of RBCs
How can renal anaemia be treated? What is the mechanism of action?
can be treated using erythropoiesis stimulating agents (ESAs)
MOA
- stimulate the proliferation and differentiation of red blood cell progenitors and preventing their apoptosis
What are the different types of erythropoiesis stimulating agents (ESAs)?
epoetins
- are recombinant human erythropoietin
- epoetin alfa = Eprex
- epoetin beta = NeoRecormon
- epoetin zeta = Retacrit
- darbepoetin
- methoxy polyethylene glycol-epoetin beta
cannot be given orally as the protein would be degraded
What are precautions for when taking epoetin?
blood pressure should be closely monitored and controlled
haemoglobin levels should be closely monitored
increased incidence of thrombotic vascular events (TVEs) have been observed in ESA use
caution in patients with epilepsy and seizures
