APPROACH TO POLYURIA AND POLYDIPSIA in children

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/m 2 /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 T he volume of urine depends upon : 1.T he amount of solute (solute load) and water ingested or produced by metabolism in excess of needs. 2.T he ability to concentrate or dilute the urine. T he ability to concetrate the urine depends on : t he presence of antidiuretic hormone ( adh ) 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: - S epto - 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 t umors 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 Genital ambiguity: -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 m osm /kg-D.I

16. 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.

17. 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%.

18. DESMOPRESSIN RESPONSE TEST

19. CONCLUSION

20. 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

21. 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

22. Complementary evaluation - Serum osmolality 300 mosm /L - Serum chloride 109 m eq /L - Serum sodium 144 m eq /L - Urine osmolality <50 mOsm /L -Urine specific gravity: 1.005 - Urine electrolytes – Sodium <5 m eq /L ; K <20 m eq /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

23. – AVP injection -Urine Osmolality And Specific Gravity Remained Low (70 And 1.005)

24. 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

25. 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

26. 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)

27. Case 3 S ix 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

28. 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