Renal Disease Flashcards
Caoimhe
5 functions of the kidneys
- Excretion of waste products -> creatinine, urea & metabolites of xenobiotics (drugs, food additives, industrial chemicals)
- Maintaining water balance
- Maintaining blood pressure
- Maintaining cardiac function -> potassium excretion
- Maintaining pH -> hydrogen ions excretion
What is the nephron
Microscopic structural & functional unit of the kidney
What is the glomerulus and what is it responsible for
A network of capillaries located at the start of the nephron. It is responsible for filtration of the blood.
Where is filtrate transported to
The Bowmans capsule and to renal tubules
What is one of the first indications of glomerular damage and why
The presence of low concentrations of albumin in the urine. Albumin is too large to fit through the pores into the ultrafiltrate and so should not be present in the urine.
What induces the pressure in the capillaries of the nephron
As the diameter of the afferent arteriole is much greater than the diameter of the efferent arteriole, a pressure is induced within the capillaries which forces molecules with small enough molecular weight into the ultrafiltrate.
Glomerular function
What happens during glomerular filtration
Removes solute from the blood. It is the first step of urine formation.
Glomerular function
What happens during tubular reabsorption
Almost all nutrients are reabsorbed in the renal tubule by active or passive transport. It is the second step of urine formation.
Glomerular function
What happens during tubular secretion
Waste products are re-secreted
What is glomerular filtrate
An ultrafiltrate of plasma. It has a similar composition to plasma without most of the proteins.
What type of glands are the adrenal glands
Endocrine glands
Functions of the adrenal glands (4)
- Osteogenesis (formation of bone) via synthesis of Vitamin D -> recquired for Calcium absorption
- Erythropoiesis (formation of rbcs) via synthesis of erythropoietin
- Maintenance of salt/water balance via the synthesis of aldosterone (mineralocorticoid)
- Regulating bodys stress response via synthesis of cortisol (glucocorticoid) & adrenaline (glucocorticoid)
What type of hormone is aldosterone
A mineralocorticoid
What are mineralocorticoids
Mineralocorticoids are a class of steroid hormones that regulate salt - water balances
What type of hormone are both cortisol & adrenaline
They are glucocorticoids
Mineralocorticoids and Glucocorticoids are types of what?
Steroid corticosteroids
How is hormonal regulation of fluid and electrolyte balance carried out? (2)
- Antidiuretic hormone (ADH) controls water reabsorption
- Aldosterone responsible for exchange of Na+ for K+
What is a major stimulus for ADH and aldosterone release
Hypovolaemia, a state of low extracellular fluid volume. This is a consequence of Renin-angiotensin-aldosterone system (RAAS) activation.
What is renal disease known as
Nephropathy
Inflammatory kidney diseases (2)
- Nephritis
- Nephritic syndrome
Non inflammatory kidney disease (2)
- Nephrosis
- Nephrotic syndrome
Pre- renal causes of renal disease (8)
- Any condition resulting in reduced blood flow to kidneys -> dehydration = low blood volume
- Severe blood/fluid loss
- Congestive heart failure, cardiovascular disease, infective endocarditis
-
Dehydration -> vomiting, diarrhoea
5.Immune mediated haemolytic anaemia (HUS ;)) - Hypertension
- Liver disease -> liver not breaking down toxins, toxins in blood will affect the kidneys
- DM
Renal causes of renal disease (4)
- Damage to renal tissue, glomerular basement membrane or tubules
- Tubular damage -> toxin exposure/ingestion
- Autoimmune diseases
- Hereditary -> polycystic kidney disease
Post-renal causes of renal disease (4)
- Obstruction to urine outflow
- Urethral stones
- Metastatic carcinomas
- UTIs
What is Acute Renal Disease (ARD) / Acute Kidney Injury (AKI)
Failure of renal function over a period of hours or days.
Lab findings for acute renal disease/ acute kiney injury (2)
- Rising serum urea
- Rising serum creatinine
What is Chronic Renal Disease (CRD)
Progressive, irreversible destruction of kidney tissue by disease. Prolonged kidney abnormalities (functional and/or structural in nature)
Tx of chronic renal disease (CRD) (2)
- Dialysis
- Transplant
Lab findings for Chronic renal disease (CRD) (5)
- Proteinuria
- Increased serum urea & creatinine
- Hypocalcaemia -> Vit D not activated
- Anaemia -> not producing erythropoietin
- Metabolic acidosis -> increased H+ conc in blood as kidneys not excreting it
Complications of kidney disease (6)
Depending on type (AKD OR CKD) & severity:
1. Metabolic acidosis & SOB -> SOB due to increased H+ ions in blood, compensatory method to try and reduce H+ ions in blood
2. Hyperkalaemia -> aldosterone synthesised by adrenal glands responsible for Na+ reabsorption and K+ excretion
3. Hypertension & heart disease
4. Oedema
5. Anaemia
6. Bone weakness -> no Vit D for intestinal Vit C absorption
Signs & symptoms of renal disease (9)
- Nausea
- Vomiting
- Anorexia
- Fatigue
- Insomnia
- Oedema -> build up of fluid in tissues
- Puritis -> itching
- High bp
- SOB
What can cause metabolic acidosis
Impaired excretion of H+ ions in renal disease
Describe the link between metabolic acidosis and shortness of breath (SOB)
- Metabolic acidosis linked to SOB via hyperventilation in an attempt to decrease CO2 and reduce plasma pH to compensate for acidosis (increased H+ ion conc)
- CO2 and H+ ions in equilibrium rxn with eachother, rxn will be pushed to the left to raise the pH again (Le Chateliers Principle)
What does mineralocorticoid deficiency CKD result in
Failure to excrete K+
What is K+ essential for (2)
- Maintaining resting membrane potential of cells
- Generating and propagating action potentials in excitable tissues
What effects on the heart may too high/low a plasma K+ conc have (3)
- Muscle weakness/paralysis
- Cardiac arrythmias
- Cardiac arrest
Explain how kidney disease can lead to heart disease
- Reduced glomerular filtration rate results in excess fluid, which results in increased blood pressure.
- High bp can damage blood vessels and arteries, causing coronary artery disease
- Heart disease is the most common cause of death among people on dialysis
Explain how kidney disease can lead to oedema
- There is a loss of albumin as a result of proteinuria. Albumin is the principal plasma protein and functions to maintain colloid osmotic pressure. With the reduced albumin, water moves out of plasma into interstitial fluid to maintain osmolality
- There is an impaired ability to excrete water. As a result of this there is water retention and water moves out of the plasma to maintain osmolality.
Explain how kidney disease leads to anaemia
- Erythropoietin synthesised in the adrenal gland
- Erythropoietin increases the number of progenitor cells committed to erythropoiesis -> increased rbcs, Hb, O2 to tissues
- Kidney disease consequence = decreased erythrocyte production
Normocytic, normochromic anaemia (problem with quantity, not quality)
How does kidney disease cause bone weakness
- The biologically active form of Vit D (calcitrol) is produced by the kidneys
- Lower levels of active Vit D cause hypocalcaemia
- Compensatory increase in PTH (hyperparathyroidism), where PTH acts to increase serum calcium via increased intestinal absorption and increased renal absorption and osteoclast activity.
Renal disease pathogenesis: Diabetes Mellitus
- Poorly managed DM
- Hyperglycaemia leads to thickening and scarring of the nephron and ultimately nephrotic syndrome
- It is the primary cause of dialysis in many developed countries
Risk factors for renal disease (10)
- Smoking
- Diet -> high animal protein, animal fat, cholesterol
- Obesity
- Genetics
- Family history
- Abnormal kidney structure
- Certain medications
- High bp
- Old age
- Uncontrolled DM
Tx of renal disease (3)
Depends on cause & stage:
1. Correction of pre renal causes
2. Nutritional therapy
3. Renal replacement therapy: dialysis & transplantation for progressed renal disease
The 2 types of renal function test
- Tests for glomerular function
- Tests for tubular function
Tests of glomerular function (5)
- Serum urea
- Serum creatinine
- Proteinuria
- Inulin clearance test
- Estimated GFR
Tests of glomerular function
How is serum urea measured
Using urease assay
Tests of glomerular function
How is serum creatinine measured
Measured using modified Jaffe procedure
Tests of glomerular function
What does a inulin clearance test measure and what is required for it
Measures glomerular filtration rate (GFR). A 24 hour urine collection is required
Tests of glomerular function
How is estimated GFR (eGFR) measured
Crockcroft-Gault and Modification of diet in renal disease (MDRD) equations