polyuria and polydipsia in a child-approach

1. APPROACH TO POLYURIA AND
POLYDIPSIA
DR.ANJANA.K.S

2. DEFINITION
• POLYURIA -defined as a urine output exceeding 3 L/day in adults
and 2 L/m2 /day or 40ml/kg/day in children.
• It must be differentiated from the more common complaints of
-frequency ,
-enuresis or
-nocturia, which are not associated with an increase in the
total urine output.

3. POLYURIA
The volume of urine depends upon:
1.The amount of solute (solute load) and water ingested or produced by metabolism in
excess of needs.
2.The ability to concentrate or dilute the urine.
The ability to concetrate the urine depends on:
1. The presence of antidiuretic hormone (adh)
2. A hyperosmolar medullary interstitium with an intact countercurrent multiplier
system

4. CAUSES OF POLYURIA:
• 1. INCREASED FLUID INTAKE
• 2. INCREASED URINARY SOLUTE EXCRETION
• 3. IMPAIRED URINARY CONCENTRATION

5. 1. INCREASED FLUID INTAKE:
- Iatrogenic
- 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

6. 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

7. • 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

8. • 2.NEPHROGENIC DIABETES INSIPIDUS:
-GENETIC:
-XL (V2 RECEPTOR DEFECT), AR, AD (AQUAPORIN DEFECT)
-ACQUIRED:
Hypokalemia,
Hypercalcemia,
Obstructive Uropathy,
Nephrocalcinosis.

9. APPROACH TO POLYURIA
• : 1.HISTORY
• 2.CLINICAL EXAMINATION
• 3.INVESTIGATIONS

10. 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
• 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.

11. HISTORY CONTINUED
• 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

12. CLINICAL EXAMINATION
• ANTHROPOMETRY:
-TO R/O FAILURE TO THRIVE : DM, DI, RTA, CAH
• FEVER:
- UTI
• MENTAL RETARDATION:
- CNS MALFORMATIONS
• NEUROLOGICAL DEFICITS:
- CNS PATHOLOGIES
• GENITALAMBIGUITY:
-CAH
• MID LINE DEFECTS:
- CENTRAL D.I

13. • FEATURES OF RICKETS:
- RENAL TUBULAR ACIDOSIS, Renal Failure
• ACIDOTIC BREATHING:
- RTA
• RASH, SEBORRHEA, EAR DISCHARGE:
-Histiocytosis
• HYPERPIGMENTATION:
-Adrenal Insufficiency
• MUSCLE WEAKNESS, FLOPPINESS:
- Hypokalemia, RTA, Bartter
ALSO LOOK FOR SIGNS OF DEHYDRATION, SHOCK

14. INVESTIGATIONS:
24 HOUR URINE OUTPUT
>5ML/KG/HR OR >2L/M2/DAY
POLYURIA
FURTHER INVESTIGATIONS

15. INVESTIGATIONS CONTINUED
• COMPLETE BLOOD COUNT
• UREA, CREATININE
• SERUM ELECTROLYTES AND CALCIUM
• CALCIUM
• BLOOD GAS ANALYSIS
• BLOOD GLUCOSE
• PLASMA OSMOLALITY
• URINE EXAMINATION FOR:
- WBCS: UTI
- Sugar: D.M
- Specific Gravity: <1.005 –D.I
-Urine Osmolality: <300 Mosm/KG-D.I

17. • LIKELY DIABETES INSIPIDUS
• HIGH PLASMA OSMOLALITY >300 MOSM/KG
• LOW URINE OSMOLALITY <300 MOSM /KG
• URINE SP.GRAVITY < 1.005
• SERUM SODIUM > 145 MMOL/L
• DIABETES INSIPIDUS UNLIKELY IF…..
• SERUM OSMOLALITY <270
• URINE OSMOLALITY >600 MOSM/KG
• URINE SP.GRAVITY >1.010
• OTHER TESTS:
• CENTRAL D.I: MRI Of Hypothalamic-pituitary Region
• NEPHROGENICD.I: Renal Imaging
• Genetic Studies As Required.

18. 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.
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%.

21. DESMOPRESSIN RESPONSE TEST

23. CONCLUSION

24. CASE 1
• 21 Months-old Boy, Chronic Gastro Esophageal Reflux
• Brought To The Office – Poor Growth
• Personal History-
- Born At Term
- Gastroesophageal Reflux Diagnosed At 3 Weeks Of Age
– Failure To Thrive At 12 Months (Despite Adequate Calory Intake)
-Height And Head Circumference -10th – 25th Percentile
• Intermittent Episodes Of Constipation –
• Frequent Colds And Ear Infections –
• Normal Development

25. • PREVIOUS EVALUATION
• CBC, Electrolytes: Normal
• Thyroid Function: Normal
• Cystic Fibrosis And Celiac Disease Screening: Negative
• Food Allergy Skin Testing: Negative
• FURTHER QUESTIONING
• Drinks 2-2.5L Of Fluid/Day
• Excessive Thirst Started At ~6 Months Of Age
• Wet Diapers: 8-10/Day Incredibly Heavy

26. • COMPLEMENTARY EVALUATION
- SERUM OSMOLALITY 300 mosm/L
- SERUM CHLORIDE 109 Meq/L
- SERUM SODIUM 144 Meq/L
- URINE OSMOLALITY <50 MOSM/L
-URINE SPECIFIC GRAVITY: 1.005
- URINE ELECTROLYTES – SODIUM <5 Meq/L; K <20 Meq/L
• ADMISSION TO THE HOSPITAL –
-WATER DEPRIVATION TEST
- Increase Of Serum Sodium (144 – 152 Meq/L)
- Increase In Serum Osmolality (297 – 310 Mosm/L)
- No Change In Urine Osmolality
- Continued Passage Of Dilute Urine (Specific Gravity <1.003)
- Weight Decreased ~5%
-Urine Output: 16 Ml/Kg/Hour

27. – AVP INJECTION
-Urine Osmolality And Specific Gravity Remained Low (70 And 1.005)

28. CASE 2
– Four Year-old Girl
• Brought To The Pediatric Nephrology Unit:
FOR Study Of Polyuria And Polydipsia
– PERSONAL HISTORY
BORN AT TERM
NO RELEVANT PREVIOUS ILLNESSES
NORMAL GROWTH (50TH PERCENTILE)
NORMAL DEVELOPMENT
NO FAMILY HISTORY OF RENAL DISEASE, POLYURIA OR DIABETES
INSIPIDUS

29. • PRESENT ILLNESS
-3 Weeks – Polydipsia (8 L Water/Day)
- Polyuria (Urine Output 9 Ml/Kg/Day)
•
• PREVIOUSLY EVALUATED –
-Suspected Of Compulsive Water Drinking
- Behavioural Approach (No Success)
LABORATORY EVALUATION
– Normal CBC
– Normal Serum Glucose, Creatinine And Urea
– Serum Sodium- 137 Meq/L; Potassium- 4.2 Meq/L; Calcium- 2.4 Mmol/L
– Venous Blood Gas: Ph- 7.39; Bicarbonate- 25.3 Mmol/L
– Urinalysis: Ph -5.5; Specific Gravity -1.005;
-No Protein, Glucose Or Ketones
– Urine Osmolality: 65 Mosm/L
– Serum Osmolality: 275 Mosm/L

30. • COMPLEMENTARY EVALUATION
– WATER DEPRIVATION TEST
- Increase In Serum Osmolality (283 – 310 Mosm/L)
- Increase In Urine Osmolality (149 – 253 Mosm/L)
-Continued Passage Of Dilute Urine (Specific Gravity 1.005) Weight Decreased ~3%
-Urine Output: 4 Ml/Kg/Hour
• AVP Injection
- Increased Urine Osmolality (784 Mosm/L) And Urine Specific Gravity (1.030)

32. CASE 3
• Six Year-old Boy, Development Delayed
• Principal Complaint – Polydipsia, Polyuria And Nocturia (Several Months)
• PERSONAL HISTORY
-3-4 Years Delayed In Language, Motor And Social Skills
PHYSICAL EXAMINATION
-Healthy well looking Child
-Height And Weight 5th – 10th Percentiles
-Normal Vital Signs
-No Abnormalities

33. • LABORATORY EVALUATION
– Normal CBC And Differential Leukocyte Count
– Serum Na 136 Meq/L; K 2.8 Meq/L; Cl 90 Meq/L
– BUN 12 Mg/Dl; Serum Creatinine 0.4 Mg/Dl
• Hands And Wrists Radiographs: Normal Bone Age
• Arterial Blood Gas: Ph 7.62; Pco2 32 (36-46); Be +11.1 (± 2.3); Total CO2 34.2 (23-
27)
• Urine: Ph- 8; Specific Gravity -1.005; No Glucose, Protein, Blood Or Ketones