What is the function of the kidneys
- Fluid balance
- Acid- base baance
- Na balance
- Excretion
- Endocrine: Ca and bones
-Activation of vitamin D
-Hormone production (renin & erythropoietin)
How do you measure normal rena function
Look at glomerular filtration rate= GFR= sum of all filtering nephrons
- assessed by insulin clearance
- plasma creatinine concentrations
What is ADH & its function
Anti-diuretic hormone
- secreted by piturity gland (detects low blood pressure)
function:
- increases water reabsoprtion
-Decreases urine output
-Increases blood volume
What is the endocrine function of the kidney
Calcium and phosphate metabolism- excretes and reabsorbs
- synthesis active vitamin D & calcitonin
- synthesis hormones renin & erythropoietin
What is diabetes mellitus
Sugar and insulin resistance
indicated by high urine output
What is diabetes insipidus
Cannot secrete ADH: large volume of dilute urine secreted
- caused by tumour/ injury to pituity
How is blood pressure controlled
renin-angiotensin system:
- regulate water & salt balance
- cause vasoconstriction & arterial blood pressure
What is the role of renin
produced by Juxtaglmerular apparatus cells (JGA)
converts Angiotensinogen- angiontensin 1
ACE catalyses angiotensin 1.> angiotensin 2
Consequence:
- Vasoconstriction (increase BP)
- Aldosterone secretion (increased water & Na retention)
-
Signs and symptoms of kidney dysfunction
low urine output
- dark urine
-proteinuria
-haematuria: renal cysts, polycystic kidney disease, trauma
- Na/ K balance
- fluid retention: oedema/ hypertension
What are the causes of acute kidney injury
pre-renal:
- impaired kidney perfusion: dehydrated, low BP, heart failure
Intra-renal:
-inflammation, embolism, scarring/ damage to nephron
- stops renal perfusion
post-renal:
-obstruction, stones
Who is at risk of acute kidney injury
- heart problems
- collapse
-pre-exisiting kidney disease
-diabetes - elderly
- trauma, unwell
Causes of chronic kidney disease
- acute kidney injury
- athersclerosis
-hypertension
-diabetes
-SLE
-Scleroderma
-Renal stones
Management of pts with kidney disease
- do not give NSAIDS as often make worse
- careful with drugs & consider how metabolised
- prevention advice : diabetes, smoking, alcohol, hypertension, athersclerosis at risk
- often anaesmic
- establish bleeding tendencies: OFTEN on coagulant for dialysis
- LA and anaemia
- Pt maybe on corticosteroids
- Best treat after dialysis
What should you consider in drug prescriptions for a pt with renal disease
Consider nephrotoxcitiy
- Erythromycin CONTRAINDICATED : (Renal transplant & circlosporin)
- Reduce doses in antimicrobials: aciclovir, amoxicillin, ampicillin, cephalexin, erythromyocin
AVOID:
- NSAIDS
-Tetracyclines
Complications of chronic kidney disease
- Anaemia: due to reduced erythropoietin (EPO)- produced by kidney. Stimulates pluripotent stem cells & maturation of RBC
- Bleeding risk:
- abnormal platelet formation, platelet vessel cell wall interaction (Virchows triad)
- Antigcoagulation for diaylsis - Calcium and bone metabolism
- Vit D required for Ca reabsroption
- Vit D is activated in kidneys
- high potassium levels can cause arrythmias
What is the link between vitamin D & PTH
Loss of negative feedback, increases parathyroid hormone
- PTH: stimulate osteoclasts (usually secreted in low calcium)
- increase bone turnover
- Giant cell lesions of bone (often in maxilla)- giant clusters in bone-> present as cytsts/ little tumours (hormone driven so will return if not addressed)
What drugs are often patients with kidney disease on?
- anticogulants
- Diuretics
- immune suppressants if kidney transplant
