PHYSIOLOGY OF THE KIDNEY

Ahmed Donia, MD, MRCP (UK)Consultant of nephrology

Urology and nephrology centerMansoura University, Egypt

RENAL BLOOD FLOW

RENAL BLOOD FLOW

21% CO

1200 ml/min

RENAL BLOOD FLOW

RENAL PLASMA FLOW

21% CO

1200 ml/min

RENAL BLOOD FLOW

RENAL PLASMA FLOW

EFFECTIVE RENAL PLASMA FLOW

21% CO

1200 ml/min

PAHNON-PRACTICAL

RENAL BLOOD FLOW

RENAL PLASMA FLOW

EFFECTIVE RENAL PLASMA FLOW

21% CO

1200 ml/min

PAHNON-PRACTICAL

RENAL BLOOD FLOW

RENAL PLASMA FLOW

EFFECTIVE RENAL PLASMA FLOW

99mTc-MAG3Renogram

21% CO

1200 ml/min

EXCRETORYENDOCRINE

Homeostasis

EXCRETORYENDOCRINE

EXCRETORYENDOCRINE

EXCRETORYENDOCRINE

EXCRETORYENDOCRINE

EXCRETORYENDOCRINE

EXCRETORYENDOCRINE

Homeostasis

EXCRETORYENDOCRINE

Urine formation

Homeostasis

EXCRETORYENDOCRINE

Glomerular filtrate

GFR=125 ml/min

GFR versus plasma clearance

Measurement

Inulin clearance (impractical) Tc-99m DTPA renogram

Estimation

Creatinine clearance

Equations

Creatinine

Estimation

Creatinine

Estimation

Creatinine

Variation in creatinine production

Dietary intake (vegetarian diet, creatine supplements) Muscle mass (amputation, malnutrition, muscle wasting)

Estimation

Creatinine

Variation in creatinine secretion

Early vs late disease

Estimation

Creatinine

Extrarenal creatinine excretion

GIT in advanced renal disease

Estimation

Creatinine clearance

Estimation

Creatinine clearance

Tubular secretion vs overestimation of cr

24 hours urine collection

Cimitidine (rarely used)

Cockcroft and Gault

Equations

Estimation

MDRD CKD-EPI

↑ 10-40% >1 equation

Underestimatenormal or mild ↓GFR

BetterIn normal GFR

Fanconi synsrome

Glycosuria

Fanconi synsrome

Glycosuria

Aminoaciduria

Fanconi synsrome

Glycosuria

Aminoaciduria

Glomerular ptnuria

Fanconi synsrome

Glycosuria

Aminoaciduria

Glomerular ptnuria

PTH ↓P reabsorption

Fanconi synsrome

Glycosuria

Aminoaciduria

Glomerular ptnuria

PTH ↓P reabsorption

RTA II

Fanconi synsrome

CAI ↓ HCO3

Glycosuria

Aminoaciduria

Glomerular ptnuria

PTH ↓P reabsorption

RTA II

Obligarory water absorption 85% (ADH independent)

Fanconi synsrome

CAI ↓ HCO3

Glycosuria

Aminoaciduria

Glomerular ptnuria

PTH ↓P reabsorption

RTA II

Obligarory water absorption 85% (ADH independent)

PAH/diodrast secretion

Fanconi synsrome

CAI ↓ HCO3

Glycosuria

Aminoaciduria

Glomerular ptnuria

↑ uric acid Diuretic (↑ reabsorption)

CKD(↓ GFR/tubular secretion)

PTH ↓P reabsorption

RTA II

Obligarory water absorption 85% (ADH independent)

PAH/diodrast secretion

Fanconi synsrome

CAI ↓ HCO3

Hypotonic fluid

Hypertonic medulla

Loop diuretic

Bartter syndrome Ca

25% Na

Thiazide diuretic

Gitleman syndrome

Ca

↑Ca absorption

5% Na

25% Na

Aldosterone

K-sparing diuretics

Thiazide diuretic

Gitleman syndrome

Ca

↑Ca absorption

5% Na

25% Na

Aldosterone

Free H

Titratable acidity

Ammonia

Distal (I) RTA

K-sparing diuretics

Thiazide diuretic

Gitleman syndrome

Ca

↑Ca absorption

5% Na

25% Na

Aldosterone

Free H

Titratable acidity

Ammonia

Distal (I) RTA

K-sparing diuretics

Thiazide diuretic

Gitleman syndrome

Ca

↑Ca absorption

5% Na

25% Na

Obligarory water absorption 85% (ADH independent)

Fuculuative water absorption 15% (ADH dependent)

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