APPROACH TO POLYURIA Dr.Padmesh.V

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

Dr.Padmesh. V

Surface area =

Ht (cm) X Wt (kg) 3600

( Daily insensible water loss = 300-

400 ml/m2 )

Dr.Padmesh. V CAUSES OF POLYURIA:

1. INCREASED FLUID INTAKE

2. INCREASED URINARY SOLUTE EXCRETION

3. IMPAIRED URINARY CONCENTRATION

Dr.Padmesh. V

CAUSES OF POLYURIA: 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

Dr.Padmesh. V CAUSES OF POLYURIA:

1. INCREASED FLUID INTAKE: Iatrogenic Compulsive water drinking (Psychogenic polydipsia)

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

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

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

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.

Dr.Padmesh. V

APPROACH TO POLYURIA:

1.HISTORY

2.CLINICAL EXAMINATION 3.INVESTIGATIONS

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

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.

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

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

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

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..

Dr.Padmesh. V INVESTIGATIONS:

24 hour urine output

>5ml/kg/hr or >2L/m2/day

POLYURIA

Further investigations

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

Dr.Padmesh. V INVESTIGATIONS: Contd…

Urea, Creatinine

Serum Electrolytes

Calcium

Blood gas analysis

Blood glucose

Plasma Osmolality

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

D.I

D.Iunlikely

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

D.I

D.Iunlikely

Dr.Padmesh. V INVESTIGATIONS: Contd…

High Plasma Osmolality <300 mOsm/kg

WATER DEPRIVATION TEST

Serum Osmolality >270

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.   

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%.

Dr.Padmesh. VWATER 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

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

Dr.Padmesh. V OTHER TESTS:

Central D.I: MRI of hypothalamic-pituitary region

Nephrogenic D.I: Renal imaging

Genetic Studies as required.

Dr.Padmesh. V

Thank you!