Overview of renal diseases Flashcards
What are the functions of the kidney?
- Excretes waste substances
- Important for acid/base balance
- Vitamin D activation
- Blood pressure control
- Red blood cell production
- Helps regulate water balance
- Regulates minerals in extracellular fluid
How do we measure kidney function?
- Blood tests
- Creatinine
- Formulae
- Urine output
- Elimination of radioisotopes
Why is the hormone that increases blood production in the kidney?
because there is a lot of blood flow to the kidney
What do people who have kidney failure therefore also suffer from?
- Vitamin D deficiency
- problems with calcium and phosphate metabolism
Why is creatinine used to measure kidney function?
- creatinine is a biomarker for the filtration of the kidney: it is a metabolic by-product of skeletal muscle (therefore muscle mass needs to be taken into consideration)
- As GFR falls (due to kidney failure), you secrete less creatinine
In what situations does the GFR need to be measured and not estimated?
- Kidney donor: if you take one kidney away, there needs to be 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: there is a very narrow therapeautic index, so need to work out the dosing (how they are cleared from the kidney)
How is GFR estimated using the CKD-EPI equation?
GFR = 141 * min (Serum_Creat/kappa, 1) alpha * max (Serum_Creat/kappa, 1) ^ -1.209 * 0.993 ^ Age * Sex * Race (White or other: 1, Black: 1.159)
What are the values used for females when estimating GFR using the CKD-EPI equation?
Sex= 1.018 alpha= -0.411 kappa= 0.9
What are the values used for males when estimating GFR using the CKD-EPI equation?
Sex= 1 alpha= -0.411 kappa= 0.9
What limitations need to be taken into consideration when estimating GFR?
- Other ethnicities
- Extremes muscle mass
- changing GFR
List some presentations of kidney disease: ‘renal syndromes’
- NephrItic syndrome
- Acute kidney injury
- Chronic kidney disease
- Haematuria
- NephrOtic syndrome
- Asymptomatic proteinuria
What is nephrItic syndrome?
Inflammatory condition in the glomerulus:
- patient has RBC in the urine
- they become hypertensive
- GFR falls: leading to kidney failure
What is nephrOtic syndrome?
Glomerular filtrate becomes very leaky:
- lots of protein in the urine: lowers serum albumin
- so there is a lowered osmotic and oncotic pressure: fluid leaks out of the periphery: peripheral odema
What is Haematuria?
Blood in the urine due to bleeding anywhere in the urinary tract- can be due to kidney stones & infection
How can acute kidney injury arise?
Kidney was working well and suddenly something happens and it dosen’t work well
What is chronic kidney disease?
Chronic decrease in GFR and this worsens over time
By what means can a single disease manifest?
In several different syndromes
List some syndromes that kidney disease can arise from?
- Accelerated hypertension
- Acute kidney injury
- Vasculitis
- Amyloidosis
- Membranous nephropathy
- IgA nephropathy
- Bacterial endocarditis
- Diabetes mellitus
- Lupus
What can a kidney biopsy provide?
A histological description which is compatible with a clinical condition and then may direct specific treatments
How is membranous nephropathy presented and what symptoms does it involve?
Usually presents as nephrotic syndrome, but can also have blood in the urine
How is IgA nephropathy presented and what symptoms does it involve?
Usually presented as nephritic syndrome, hypertension in the blood and kidney failure
What is bacterial endoocarditis?
Chronic infection in the heart valves, results in complex disposition in the kidney
~ presented as nephritic syndrome
Effect of diabetes on the kidney?
Chronic damage to the kidney due to high blood sugae
How is Lupus categorized?
Nephritic
How is Amyloidosis categorised?
Nephrotic
How is Vasculitis categorised?
Nephritic
How is Acute kidney injury categorised?
Oliguria or no urine
How is accelerated hypertension categorised?
Systemic problem, e.g. vasculitis with nephritic syndrome
What does a kidney biopsy provide?
A histological description which is compatible with a clinical condition and then may direct specific treatments
Describe approaches to renal disease
see table in notes
Use a graph to describe levels of serum creatinine that indicate the severity of different types of kidney disease
see notes
What % of Acute Kidney Injuries is affected in emergency admissions?
20%
What % of AKI may be preventable?
20-30%
What is the % mortality ration AKI?
25-40%
-even minor increases in Cr results in increases in mortality
Pre-renal causes of kidney disease
Not delivering enough blood to the kidney, intrinsic kidney disease
Post-renal causes of kidney disease
Blockage in the kidney: urine not leaving
List 3 pre-renal causes
- Hypovolaemia
- Decreased perfusion
- Drugs
Hypovolaemia
- most common pre-renal cause
- symptoms:
- haemorrhage
- diarrhoea/vomiting
Decreased perfusion
- kidney is the most susceptible to ischaemic damage ~ kidney makes erythropoietin from the start
- Parts of the tubule are borderline hypoxic, so if the kidney is under perfused, then there will be some kidney damage
- symptoms:
- septic shock
- cardiac failure
Septic shock
is a serious medical condition that occurs when sepsis, which is organ injury or damage in response to infection, leads to dangerously low blood pressure and abnormalities in cellular metabolism.
Drugs as a pre-renal cause
Some drugs interfere with the homeostatic mechanisms that protect the kidney from being under perfused
- Angiotensin converting inhibitors
- Non steroidal anti-inflammatory drugs, e.g. ibroprofen
