CKD Flashcards
CKD - pathophysiology, causes / rf
chronic reduction in kidney function- permanent and progressive. subtle decrease in OVER 3 months (AKI <3months)
causes:
1. Diabetes= excess gluose sticks to protein (nonenzymatic glycaration) effecting the efferent arteriole to be stiff and narrow. diffiuclt for blood to leave so gets forced through hyperfiltration.
- Hypertension- walls of the artery thicken to withstand high pressure= narrow= less blood to o2- ischaemic damage to glomerulus. foam cells and macrophage.
- Age-related decline
lupus, - RA
- Glomerulonephritis
- Polycystic kidney disease
- Medications such as NSAIDS, proton pump inhibitors and lithium
- infection (HIV)
risk factors: Older age Hypertension Diabetes Smoking Use of medications that affect the kidneys
CKD presentation / clinical features
asymptomatic (routine testing)
pruritus (uraemia) loss of appetite nausea oedema muscle cramps peripheral neuropathy pallor hypertension
CKD investigations
bedisde:
haematuria
urine dipstick
1+ bood. (rule out malignancy)
bloods:
eGFR
U+E’s
*two testes are required 3 months apart to confirm CKD
creatinine level
**estimates how quickly kidneys are filtering blood and producing urine
proteinuria
urine albumin: creatinine ratio >3mg/mmol is significant
(normally expect for kidneys to filter creatinine but its not normal for albumin to end up in the urine because this is a bigger protein)
imaging:
renal ultrasound- investigate accelerated chronic kidney disease
stages of CKD
G score (eGFR) (glomerular filtration rate)
G1 = eGFR >90 G2 = eGFR 60-89 G3a = eGFR 45-59 G3b = eGFR 30-44 G4 = eGFR 15-29 G5 = eGFR <15 (known as “end-stage renal failure”)
A score (albumin:creatine ratio) (measure of proteinuria)
A1 = < 3mg/mmol A2 = 3 – 30mg/mmol A3 = > 30mg/mmol
eFR <60 or proteinuria for a diagnosis of CKD
referral CKD
NICE suggest referral to a specialist when there is:
eGFR < 30
ACR ≥ 70 mg/mmol
Accelerated progression defined as a decrease in eGFR of 15 or 25% or 15 ml/min in 1 year
Uncontrolled hypertension despite ≥ 4 antihypertensives
complications of CKD
Anaemia Renal bone disease Cardiovascular disease Peripheral neuropathy End stage kidney disease Dialysis related problems
*urea not filitered out so more in blood. azotemia, nausea, loss of appetitie. if effects CNS- ecenphalopathy, esterixis.
management of CKD
- slow progression of the disease
- optimise diabetic control
- optimise HTN control
- treat glomerulonephritis - reduce the risk of complication
exercise, healthy weight, stop smoking, dietary advice K+, PO, Na+, H2o
atorvostatin20mg for primary CVD - managing complications:
oral sodium bicarbonate (to treat metabolic acidosis)
iron (erythropoietin to treat anaemia)
vitamin D renal bone disease
dialysis end-stage renal failure
renal transplant in end-stage renal failure
anaemia of CKD
healthy cells produce erythropoietin which stimulates the production of RBC. if kidney cells are damaged in CKD- drop in erythropoietin- drop in RBC = (normocytic) anaemia
if microcytic then this could be due to iron deficiency
exogenous erythropoietin
blood transfusion- sensitise the immune system (allosensitsation) (give externally produced EPO to stimulate production of RBC)
limit blood transfusion incase having kidney transplant as more likely to be rejected in future
if iron deficiency IV iron then treat this before EPO
renal bone idsease
CKD- mineral and bone disorder
osteomalacia
osteoporosis (brittle)
osteosclerosis (hardening of bones)
xray: spine xray shows sclerosis (dense and white at both ends of vertebrae)
osteomalacia (centre of vertebra - less white)
rugger jursey spine
pathophysiology of mineral and bone disorder in CKD
High serum phosphate occurs due to reduced phosphate excretion.
Low active vitamin D because the kidney is essential in metabolising vitamin D to its active form. (Active vitamin D is essential in calcium absorption from the intestines and kidneys. Vitamin D also regulates bone turnover.)
Secondary hyperparathyroidism occurs because the parathyroid glands react to the low serum calcium and high serum phosphate by excreting more parathyroid hormone. (to increase the amount of ca2+ in the blood via GI/kidney/bones) This leads to increased osteoclast activity. Osteoclast activity lead to the absorption of calcium from bone.
Osteomalacia occurs due to increased turnover of bones without adequate calcium supply.
Osteosclerosis occurs when the osteoblasts respond by increasing their activity to match the osteoclasts by creating new tissue in the bone, however, due to the low calcium level, this new tissue is not properly mineralised.
Osteoporosis can exist alongside renal bone disease due to other risk factors such as age and use of steroids.
manage:
with active forms of vitamin D (alfacalcidol and calcitriol)
Low phosphate diet
Bisphosphonates can be used to treat osteoporosis
*drop in GFR so kidneys sense this as low BP so secrete more renin= vicious cycle.
renal transplant
A renal transplant is placed in the right or left iliac fossa with vascular anastomoses on the iliac vessels. The transplant ureter is anastomosed to the bladder, and often a ureteric stent is placed at operation. The operation usually lasts 90 minutes. Postoperative care is focused on accurate blood pressure and fluid balance management, pain relief, and early mobilisation. Immunosuppression is titrated, and patients are monitored for early signs of rejection. The donor kidney can be injured by the events leading to donor death, the retrieval operation, ischaemia, and reperfusion in the recipient.
signs of renal failure:
Uraemia Acidosis Fluid overload Hypertension Hyperkalaemia Hypocalcaemia, hyperphosphataemia Drug toxicity Anaemia
normal physiological response to decreased blood volume
Afferent vasodilation prostaglandins, NO Efferent vasoconstriction Angio II, Noradrenaline, local myenteric response Increased salt and water retention Renin Aldosterone System ADH
rhabdomyolysis
CK > 20,000 Often > 100,000 Ensure hydrated Consider alkalinization of urine Consider diuretics + fluids!
assessing fluid balance
Pulse Blood pressure JVP Skin turgor Capillary refill Thirst Oedema
