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2. polyuria
 excessive or abnormally large production
and/or passage of urine (>3 L per day in
adults).
 Frequent urination – accompanying
syndrome
 Diuresis – increased production and passage
of urine

3. Mechanisms of polyuria
 Due to excretion of increased
nonabsorbable solutes(such as glucose)
– SOLUTE DIURESIS
 Due to excretion of increased
water(from a defect in ADH production
or renal responsiveness) – WATER
DIURESIS

4. Water diuresis
 Urine output >3 L per day
 Urine is dilute (<250 mosmol/ L)
 Causes – polydipsia , central diabetes
insipidus , nephrogenic diabetic
insipidus

5. Solute diuresis
 Urine output > 3 L per day
 Urine osmolarity > 300 msmol/L
 Causes – increased glucose,mannitol or
urea medullary cystic
diseases,obstruction,diuretics

6. TYPES OF POLYURIA
I. pathological polyuria
 Polyuria caused by a disease of the
kidney or disorder anywhere in the body
eg. Diabetes mellitus, diabetes
insipidus,liver failure

7. II. Pharmacological polyuria
 Polyuria caused by administerd fluids or
by medication such as glucocorticoids or
diuretics

8. III. Physiological poyuria
 Compensatory mechanism to increased
fluid intake
 Cold diuresis – in hypothermia as a
result of peripheral
vasoconstriction,hyperglycemia and
decresed renal tubular reabsorption
 Altitude diuresis

9. polydipsia
 Increase in thirst
 Often appear in conjugation with
polyuria
 It can either be cause or effect of
polyuria

10. Psychogenic polydipsia
 Also called primary polydipsia
 Patient intakes increased amount of fluid
due to sensation of having a dry mouth
 Most commonly due to phenothiazine
medication used in mental disorders

11. Diabetes insipidus
 Disorder that causes polyuria
 due to impaired urinary concentrating
ability leading to increased free water
clearance
 Polydipsia present
 Plasma sodium may be normal

12. .
 Free water is the water free of solutes
 Free water clearance = urine flow rate –
osmotic clearance
 Osmotic clearance = urine flow rate x
urine osmolality/plasma osmolality

13. Two types of DI
 Central DI – amount of ADH produced
by the pituitary is below normal
 Nephrogenic DI – kidney’s ability bto
respond to ADH is defective