1. Polyuria is defined as urine output greater than 5 ml/kg/hr or 2 L/m2/day. Causes include increased fluid intake, increased urinary solute excretion, and impaired urinary concentration. 2. Evaluation of polyuria involves obtaining a detailed history, clinical examination, and investigations including a 24-hour urine output measurement and urine and serum analysis. 3. Distinguishing between central and nephrogenic diabetes insipidus involves tests like the water deprivation test and vasopressin response test.

1. APPROACH TO POLYURIA Dr.Padmesh.V

2. Dr.Padmesh. V
 Definition of Polyuria:
Urine output > 5 ml/kg/hr
Or
> 2 L/m2/day
Definition of Oliguria:
Urine output < 0.5 – 1 ml/kg/hr
Or
< 300 ml/m2/day

3. Dr.Padmesh. V
 Surface area =
Ht (cm) X Wt (kg)
3600
( Daily insensible water loss = 300-400 ml/m2 )

4. Dr.Padmesh. V
 CAUSES OF POLYURIA:
 1. INCREASED FLUID INTAKE
 2. INCREASED URINARY SOLUTE EXCRETION
 3. IMPAIRED URINARY CONCENTRATION

5.  CAUSES OF POLYURIA: Dr.Padmesh. V
 1. INCREASED FLUID INTAKE
1.Iatrogenic
2.Compulsive water drinking (Psychogenic polydipsia)
 2. INCREASED URINARY SOLUTE EXCRETION
 OSMOTIC DIURESIS:
1.Diabetes mellitus
2.Mannitol treatment
 SALT LOSS:
1.Adrenal insufficiency
2.Diuretics
3.Cerebral salt wasting
4.Aldosterone resistance
 3. IMPAIRED URINARY CONCENTRATION
 INEFFICIENT ADH ACTION: (DIABETES INSIPIDUS):
1.CENTRAL (NEUROGENIC) DIABETES INSIPIDUS:
2.NEPHROGENIC DIABETES INSIPIDUS:
 RENAL DISORDERS:
1.Renal Tubular acidosis
2.Bartter Syndrome
3.Gitelman Syndrome

6. Dr.Padmesh. V
 CAUSES OF POLYURIA:
 1. INCREASED FLUID INTAKE:
 Iatrogenic
 Compulsive water drinking (Psychogenic polydipsia)

7. Dr.Padmesh. V
 CAUSES OF POLYURIA:
 2. INCREASED URINARY SOLUTE EXCRETION:
 OSMOTIC DIURESIS:
1.Diabetes mellitus
2.Mannitol treatment
 SALT LOSS:
1.Adrenal insufficiency
2.Diuretics
3.Cerebral salt wasting
4.Aldosterone resistance

8. Dr.Padmesh. V
 CAUSES OF POLYURIA:
 3. IMPAIRED URINARY CONCENTRATION:
 INEFFICIENT ADH ACTION: (DIABETES INSIPIDUS):
1.CENTRAL (NEUROGENIC) DIABETES INSIPIDUS:
2.NEPHROGENIC DIABETES INSIPIDUS:
 RENAL DISORDERS:
1.Renal Tubular acidosis
2.Bartter Syndrome
3.Gitelman Syndrome

9. Dr.Padmesh. V
 CAUSES OF POLYURIA:
 3. IMPAIRED URINARY CONCENTRATION:
 INEFFICIENT ADH ACTION: (DIABETES INSIPIDUS):
1.CENTRAL (NEUROGENIC) DIABETES INSIPIDUS:
-Genetic defects: AR, AD, Wolfram DIDMOAD Synd.
-Malformations: Septo-optic dysplasia,
Holoprosencephaly,Anencephaly.
-Neurological insults: Head trauma, Neurosurgery,
Infection,Brain death.
-Infiltrative disorders: Sarcoidosis, Histiocytosis.
-CNS tumors: Craniopharyngioma, Germinoma,
Pinealoma

10. Dr.Padmesh. V
 CAUSES OF POLYURIA:
 3. IMPAIRED URINARY CONCENTRATION:
 INEFFICIENT ADH ACTION: (DIABETES INSIPIDUS):
2.NEPHROGENIC DIABETES INSIPIDUS:
-Genetic: XL (V2 receptor defect), AR,
AD (Aquaporin defect)
-Acquired: Hypokalemia, Hypercalcemia,
Obstructive uropathy, Nephrocalcinosis.

11. Dr.Padmesh. V
APPROACH TO POLYURIA:
1.HISTORY
2.CLINICAL EXAMINATION
3.INVESTIGATIONS

12. Dr.Padmesh. V
 HISTORY:
 Age of onset: Congenital / Acquired
 H/O fever: UTI
 Failure to thrive: DM, Nephrogenic D.I, RTA, CAH, Bartter
 H/O head trauma,neurosurgery: Central D.I
 H/O meningitis: Central D.I

13. Dr.Padmesh. V
 HISTORY: contd…
 H/O weight loss: DM, RTA
 H/O rash,seborrhea: Histiocytosis
 H/O muscle weakness: Hypokalemia- RTA, Bartter
 H/O drug intake: Mannitol, Diuretics, out-dated Tetracyclines.

14. Dr.Padmesh. V
 HISTORY: contd…
 Symptoms of increased ICT: CNS tumors
 H/O polyuria, shock in newborn period: CAH
 H/O constipation,paresthesia: Hypercalcemia
 H/O psychological problems: Psychogenic polydipsia
 H/O abdominal cramps, arthralgia, etc: Sickle cell anemia

15. Dr.Padmesh. V
 CLINICAL EXAMINATION:
 Anthropometry: To r/o Failure to thrive : DM, DI, RTA, CAH
 Fever: UTI
 Mental retardation: CNS malformations
 Neurological deficits: CNS pathologies

16. Dr.Padmesh. V
 CLINICAL EXAMINATION:
 Genital ambiguity: CAH
 Mid line defects: Central D.I
 Features of Rickets: Renal Tubular Acidosis, Renal failure
 Acidotic breathing: RTA

17. Dr.Padmesh. V
 CLINICAL EXAMINATION:
 Rash, Seborrhea, ear discharge: Histiocytosis
 Hyperpigmentation: Adrenal insufficiency
 Muscle weakness,neck flop: Hypokalemia: RTA, Bartter
 Also look for signs of dehydration, shock..

18. Dr.Padmesh. V
 INVESTIGATIONS:
24 hour urine output
>5ml/kg/hr or >2L/m2/day
POLYURIA
Further investigations

19. Dr.Padmesh. V
 INVESTIGATIONS: Contd…
 Urine examination for:
 WBCs: UTI
 Sugar: D.M
 Specific gravity: <1.005 – D.I
 Urine Osmolality: <300 mOsm/kg- D.I

20. Dr.Padmesh. V
 INVESTIGATIONS: Contd…
 Urea, Creatinine
 Serum Electrolytes
 Calcium
 Blood gas analysis
 Blood glucose
 Plasma Osmolality

21. Dr.Padmesh. V
 INVESTIGATIONS: Contd…
 High Plasma Osmolality >300 mOsm/kg
 Low Urine Osmolality <300 mOsm /kg
 Urine Sp.gravity < 1.005
 Serum Sodium > 145 mmol/L
 Serum Osmolality <270
 Urine Osmolality >600 mOsm/kg
 Urine Sp.gravity >1.010

22. Dr.Padmesh. V
 INVESTIGATIONS: Contd…
 High Plasma Osmolality >300 mOsm/kg
 Low Urine Osmolality <300 mOsm /kg
 Urine Sp.gravity < 1.005
 Serum Sodium > 145 mmol/L
 Serum Osmolality <270
 Urine Osmolality >600 mOsm/kg
 Urine Sp.gravity >1.010

23. Dr.Padmesh. V
 INVESTIGATIONS: Contd…
 High Plasma Osmolality <300 mOsm/kg
WATER DEPRIVATION TEST
 Serum Osmolality >270

24. Dr.Padmesh. V
 WATER DEPRIVATION TEST
-Determines ability of kidneys to concentrate urine.
-Useful in the diagnosis of DI.
-Requires careful supervision because dehydration and
hypernatremia may occur.

25. Dr.Padmesh. V
WATER DEPRIVATION TEST : Method:
 Begin the test after a 24-hr period of adequate hydration &
stable weight.
 Obtain a baseline weight after bladder emptying.
 Restrict fluids for 7 hours.
 Measure body weight and urine specific gravity and volume
hourly.
 Check serum Na+ and urine and serum osmolality every 2 hr.
 Terminate the test if weight loss approaches 5%.

26. Dr.Padmesh. V
WATER DEPRIVATION TEST: Interpretation:
Normal individuals & Psychogenic DI: Central or Nephrogenic DI:
When water is deprived
Will concentrate urine (to 500-1400 mOsm/L) Urine osmolality remains <150-300 mOsm/L
Plasma osmolality will be 288-291 mOsm Plasma Osmolality > 300 mOsm
Urine specific gravity rises to at least 1.010 Urine Specific gravity remains <1.005
Urine volume decreases significantly No significant reduction of urine volume
There will be no appreciable weight loss. Weight loss of up to 5% usually occurs

27. Dr.Padmesh. V
 VASOPRESSIN RESPONSE TEST:
To differentiate CENTRAL D.I from NEPHROGENIC D.I
Baseline Urine osmolality is recorded
Vasopressin injection given
Urine Osmolality measured at 1 hr & 4 hrs after injection
Increase in urine osmolality
>50% increase from baseline <50% increase from baseline
CENTRAL D.I NEPHROGENIC D.I

28. Dr.Padmesh. V
 OTHER TESTS:
 Central D.I: MRI of hypothalamic-pituitary region
 Nephrogenic D.I: Renal imaging
 Genetic Studies as required.

29. Dr.Padmesh. V