overview of renal diseases Flashcards
What are the functions of the kidney?
- BP control
- EPO production (RBC production)
- acid base balance
- Vit D activation
- excretes waste substances
- regulates minerals in extracellular fluid
where is Na+ mostly reabsorbed?
PCT
where is K+ mostly reabsorped/secreted?
DCT
which part of the nephron is a modified capillary bed?
glomerulus
how do we measure kidney function?
Blood tests
-Creatinine (a metabolic by-product of skeletal muscle, as GFR falls you secrete less creatinine)
-Formulae, estimate GFR using the Cockcroft gault equation which takes into account the age, gender and weight, or the
MDRD equation (the modification of diet in renal disease)
Urine output
Elimination of radioisotypes
most accurate way = inulin, but it is expensive
give 2 situations where you would need to estimate GFR:
Kidney donor
-if you take one kidney away, you need to work out GFR to see if there is enough function in the other kidney to allow the body to function properly, and to see if the kidney is a good enough donor
Cancer patient using chemotherapeutic drugs
-very narrow therapeutic index, work out GFR so you can work out the dosing, based on how they are cleared from the kidney
what indicates kidney damage
presence of blood/proteins in the urine
Presentations of kidney disease
“Renal syndromes”
- Nephritic syndrome: inflammatory condition in the glomerulus, person has RBCs in the urine, they become hypertensive and their GFR falls because arterioles get damaged, leading to kidney failure
- Nephrotic syndrome: glomerular filtrate becomes very leaky, lots of protein in the urine which lowers serum albumin and lowers the oncotic pressure, so fluid leaks out into the periphery - peripheral odema
- Haematuria – blood in the urine due to bleeding anywhere in the urinary tract (due to kidney stones, infection)
- Acute kidney injury – kidney was working well and suddenly something happened and it doesn’t work well
- Chronic kidney disease – chronic decrease in GFR - this worsens over time
Patients can present with overlap between all the symptoms
nephritic syndrome can present itself in which diseases?
Vasculitis
Lupus
Bacterial endocarditis
IgA nephropathy
nephrotic syndrome can present itself in which diseases?
Amyloidosis
Membranous nephropathy
diabetes causes
chronic damage to the kidney due to high blood sugar
what happens in cardiogenic shock
the heart cannot pump enough blood to meet body’s need.
if the kidneys are not functioning properly, how will that affect creatinine levels?
serum creatinine levels will increase as creatinine will accumulate in the blood
how does serum creatinine increase?
exponentially
why might serum creatinine levels increase?
not perfusing the kidney for a period
- can happen due to a surgery, or if the person has been severely bleeding
- dried out through vomiting or diarrhea, because this would lead to increased ADH levels and decreased urine volume
pre-renal vs post-renal causes of kidney disease
Pre-renal = not delivering enough blood to the kidney/intrinsic kidney disease
Post-renal = blockage of the urinary tract which causes back pressure in the kidney, urine not leaving
pre-renal causes
Hypovolaemia
- Haemorrhage
- Diarrhoea/vomiting
↓Perfusion (parts of the tubule are borderline hypoxic, so under perfused kidney = kidney damage)
- Septic shock
- Cardiac failure
Drugs
- Angiotensin converting inhibitors
- Non steroidal anti-inflammatory drugs (inhibit PG’s needed for vasodilation)
Intrinsic renal disease (pre-renal)
- glomerulonephritis
- acute tubular necrosis
-interstitial nephritis, an inflammatory infiltrate with lymphocytes in the interstitial spaces in the kidney, typically presents as kidney failure
looking for signs of glomerular diseases
- urine analysis (blood & protein)
- urine stick testing, looking at urine albumin : creatinine ratio - red cell casts - RBCs become clustered together in the tubule after they leak (they take the shape of the tubule)
- when RBCs squeeze through the glomerular filter they become deformed glomerular/dysmorphic erythrocytes
urine protein:creatinine ratio is more specific
post-renal
- Distention (enlargement) of the ureter – hydroureter
- Distention of the collecting system - hydronephrosis
Acute Kidney Injury (AKI)
can be pre-renal, intrinsic or post renal
what can AKI cause?
fluid retenton
-peripheral odema and pulmonary odema
-pulmonary odema is fluid in the air spaces of the lungs, caused when the patient is not excreting enough water, so more high blood pressure goes back to the heart, increasing the pressure in the heart – that blood is pumped to the lungs, and leakage of fluid into the alveoli spaces, causing hypoxia
what can AKI cause? (K+)
kidneys failing means excess K+ cannot be excreted so it build up in the body
plasma K+ is usually kept at a very narrow range, usually K+ is higher in the cells than out
high serum K+ reduces the electrochemical gradient across the cell membranes (salty banana) - more difficult for AP’s to generate in the heart (cardiac arrhythmias)
What are the consequences of AKI?
Significant impact on outcome
Hospital mortality / post-discharge mortality
Resources:
length of stay (ICU/hospital)
referrals / tests / treatment
Patient morbidity:
acute complications
dysfunction of other organs
risk of CKD
when being on a transplant list, what does suspended mean?
someone was on the list for a transplant but taken off as they were deemed “not fit”
as the population in need for a transplant is getting older, many of them are unable to go through with the transplant
kidney failure is a ________ risk factor
cardiovascular (especially chronic kidney failure)
As eGFR falls cardiovascular risk increases
chronic kidney disease can contribute to which disease?
atherosclerosis
CKD can cause the following which contribute to atherosclerosis
- calcification
- lipoprotein remnants
- parathyroid hormone, released in response to high phosphate levels and low vit D levels, leads to hypertrophy of the myocardium
- pulse pressure, due to increased stiffening in the blood vessel walls, the gap between the systolic pressure and the diastolic pressure widens
- homocysteine build up, which damages the heart
Treatment of CKD
Supportive care
- General measures
- Dialysis
- Transplantation
Treatment of underlying condition - used more and more due to elderly patients
management of chronic renal failure
-Conservative
slow progression
minimise symptoms/complications
-Control Na+, water, BP
-Diet (K+, phosphate, {protein})
-Vitamin D (1-alpha)
-ErythropoetinHaemodialysis - role?
- Removes nitrogenous wastes
- Corrects electrolytes
- Removes water
- Correct acid base abnormalities
connecting to a haemodialysis machine:
- AV fistula
-Vein joined onto artery – arteriole flow in a large vein makes the vein bigger, and high flow in the vein. This makes it easier to transfer your blood into the dialysis machine and back again.
Permenant access. - Haemodialysis catheter
- Inserted into the internal jugular vein – and goes down into the atrium. Temporary access
how does haemodialysis remove toxins
Having them in different directions maximises the concentration gradient
Waste products migrate out through the semi permeable membrane into dialysis flow (creatinine and urea)
IgA and Albumin don’t cross into dialysis flow
Bicarbonate goes in the opposite direction (into blood)
peritoneal dialysis
inside lining of your own belly (the peritoneal) is used as the semi-permeable membrane
-acts as a natural filter
Transplantation
Deceased donor – brain death (DBD), organs are still well perfused
Deceased donor – cardiac death (DCD), kidneys aren’t perfused
Living donor:
- Related (biological, emotional, social)
- Kidney sharing scheme -switch donors ~ usually when the donor is not suitable
- Altruistic - just offering to donate
- ABO/HLA incompatible - avoid rejection
what affects mortality
dialysis
kidney biopsy
a procedure that involves taking a small piece of kidney tissue for examination with a microscope.
looking for a kidney disease summary of steps
- Measure eGFR (use creatinine as a biomarker)
- Is there blood / protein in the urine (urine testing)
- Is this intrinsic renal disease?
- What is the tempo of the disease? (timescale, acute or chronic)
- What is the kidney size? (normal is 10-12cm, if it goes down to 7cm, you’ve got end stage kidney failure)
- Biopsy
- General & specific treatments
- Manage consequences of
- poor eGFR
- Vit D deficiency
- Lack of erythropoietin
- Dialysis, transplantation, conservative
