All things Renal

Peer SupportZoulikha Zair

RAAS

Components of the RAAS• Renin

– Synthesised and stored in the JGA– Released in response to low BP and low NaCl in filtrate

• Angiotensin II– Vasoconstriction– increased PT Na+ reabsorption (indirect via Aldo. in DT)– induces aldosterone production

• Aldosterone and Sodium Reabsorption– Aldosterone induces expression and activity of SGK (serum and

glucocorticoid regulated kinase) – which causes translocation of ENaC to membrane and

expression– driving force is Na+/K+ATPase (activity also increased by

aldosterone)

How is bp increased?

GFR and eGFRGlomerular filtration rate • Linked to age, sex and body size

– young male = 120ml/min/1.73m2

– lower in females and decreases with age• total volume filtered is ~180 l/day• Regulated by constriction/dilatation of the afferent arteriole (AA)• (if AA is dilated the GFR increases and hydrostatic pressure in the glomerulus )

Estimated GFR• the volume of blood plasma that is cleared of creatinine per unit time• Incorporates, age, sex and ethnicity • Utilises MDRD = modification of diet in renal disease

(µmol/L)

What is Acute Kidney Failure?

• A sudden (hours to weeks) decline in glomerular filtration rate marked by the accumulation of metabolic waste products with life threatening consequences.

Name three classifications of AKI

• Pre-renal - kidneys don’t receive adequate blood supply– Renal hypoperfusion– Local e.g. Renal artery stenosis, Drugs- ACE

inhibitors, NSAIDs• Intrinsic – Kidney tissue becomes damaged– Acute tubular injury e.g. ischaemia– Acute glomerulonephritis

• Post-renal – obstruction to urinary flow

What ic Chronic Kidney Disease?

• Progressive and irreversible loss of renal function over a period of years or months, resulting in the loss of both excretory and hormone functions of the kidney.

How is CKD Classified?

• Diagnosis/Classification of CKD is based on eGFR plus evidence of other chronic kidney damage;– Persistent microalbuminaemia– Persistent proteinuria– Persistent haematuria after exclusion of other causes– Structural abnormalities of the kidneys shown by

radiology– Biopsy proven glomerulonephritis