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"P. & A. Kyriakou" Children's Hospital, Athens . Division of Pediatric Nephrology . The polyuric child When we worry?. ESPN, Lyon-Sept.2008. Andromachi Mitsioni Departement of Pediatric Nephrology ”P. & A. Kyriakou” Children’s Hospital Athens - GREECE.

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the polyuric child when we worry

"P. & A. Kyriakou" Children's Hospital, Athens

Division of Pediatric Nephrology

The polyuric childWhen we worry?

ESPN, Lyon-Sept.2008

Andromachi Mitsioni

Departement of Pediatric Nephrology

”P. & A. Kyriakou” Children’s Hospital

Athens - GREECE

polyuria is defined as an increase in total daily outpout of urine
Urine outpout > 40 ml/kg/24h

or > 2000 ml/m2/24h

preschool children>1l/24h

school children>2l/24h

adults >3l/24h

POLYURIA is defined as an increase intotal daily outpout of urine
polyuria
Polyuria
  • Distinguish from:

frequent micturition

nocturia

enuresis

  • Are not associated with an increase in the total urine output
polyuria4
Polyuria

The volume of urine depends upon:

1.The amount of solute (solute load) andwater ingested or produced bymetabolism in excess of needs

2.The ability to concetrate or dilute theurine

the ability to concetrate the urine depends on
The ability to concetrate the urinedepends on:
  • the presence of antidiuretic hormone(ADH) and
  • A hyperosmolar medullary interstitium

with an intact countercurrent multiplier

system

slide6

1.Active sodium chloridetransport in the thick ascending limb of loop of Henle (TΑL)

5.In the presenceof ADH, collectingtubule highlypermeant to water

TΑL

3. Water permeablesegment in the thin descending limb of loop of Henle

4. Urea reabsorption in the collecting tubule

2. Passive reabsorption of sodium in the thin ascendinglimb of loop of Henle

polyuria7
POLYURIA
  • Water diuresis(urine osmolality

<250mOsm/kg)

  • Solute diuresis(urineosmolality

>250 mOsm/kg)

  • More than one abnormality may be present in any form of polyuria
water diuresis may be due to
Water diuresis may be due to:
  • PRIMARY POLYDIPSIA
  • DIABETES INSIPIDUS

Neurogenic(failure of neurohypophysisto synthesize or secrete ADH)

Nephrogenic(failure of the kidney torespond appropriately to ADH)

  • partial to complete
primary polydipsia
Primary polydipsia
  • Compulsive water drinking

(rare in children,most commonly in adolescents with a psychological distiburbance)

  • Treatment with large quantities ofwater

(treatment of nephrolithiasis , or with drugs as CP)

  • Defect in the thirst center (in thehypothalamus of CNS)

Excessive fluid intake will supress vasopressin secretion and induce

polyuria (normoNa patients with normal or reduced plasma osmolality)

diabetes insipidus
DIABETESINSIPIDUS
  • Neurogenic (central) DI

Primary

Secondary

  • Nephrogenic DI

Congenital (hereditary)

Acquired(Secondary)

neurogenic central diabetes insipidus primary
NEUROGENIC (CENTRAL)DIABETES INSIPIDUSPRIMARY
  • Idiopathic(30-50% in children)

autoimmune process

+/-presence of cytoplasmic antibodies against VS

  • Familial(5% )

autosomal dominant disease caused by mutations

in the arginine-vasopressin gene(chromosome 20)

  • DIDMOAD (Wolfran syndrome)

Neurogenic DI,Diabetes Mellitus,Optic Atrophy

Deafness.

autosomal recessive trait

neurogenic central diabetes insipidus secondary
NEUROGENIC(CENTRAL)DIABETES INSIPIDUSSECONDARY

Neurosurgery

Trauma (head injury)

Infection(meningitis,encephalitis,CNS abscess,congenital infection.)

Tumor(craniopharyngioma,glioma ,germinoma,metastasis)

CNS granulomatous disease(sarcoidosis,,histiocytosis X)

Hypoxia

Intracranialhemorrhage(aneurysm,thrombosis,embolus)

Drugs (phenyntoin,clonidine,alcohol)

nephrogenic diabetes insipidus hereditary congenital
NEPHROGENIC DIABETES INSIPIDUSHEREDITARY(CONGENITAL)
  • a PURE type characterized by loss ofwater only
  • a COMPLEX type characterized by loss of water and ions(Na+,Cl-,Ca++,K+,Mg+)
peter agre and roderick mckinnon the 2003 nobel prize in chemistry answered 2 questions
Peter Agre and Roderick McKinnon, (the 2003Nobel Prize in Chemistry) answered 2 questions
  • How does a cell let one type of ion through

the lipid membrane to the exclusion ofothers?

  • How does water permeate the cell withoution?

These 2 problems are relevant to the molecular understanding of 2 types of hereditarynephrogenic DI

mechanisms for blocking proton permeation by aquaporin
Mechanisms for blocking proton permeation by aquaporin
  • The water channels letwater go through but not protons. Protons are jumping from one water molecule to another, but due to the special arrangement of these two asparagines ,there is a link and the protons cannot jump to the next water molecule.
pure gongenital nephrogenic di
PURE Gongenital Nephrogenic DI
  • X-linked(90-95%)

mutation of V2 receptor gene (AVPR2)

chromosome region Xq28

  • Autosomal dominant or autosomal recessive

5-10% of patients

mutation of aquaporin 2 gene (AQP2)

chromosome region 12q13

slide20
COMPLEXE Nephrogenic diabetes insipidusSeparation of salt and water in thick ascendinglimb (TAL) of loop of Henle
slide21

ABNORMALITIES IN ANY OF THESE PROTEINSOF THE TALCANLEAD TO SALT –LOSINGNEPHROPATHY

As a result of these different molecular alterations:

  • NaCl is lost into the lumen
  • positive voltage is abolished
  • Ca++,Mg++ ,K+,NH4+ cannot be reabsorbed in theparacelullar space
  • COMPLEX POLYURIC DISORDERS
neprhogenic diabetes insipidus secondary
NEPRHOGENIC DIABETES INSIPIDUSSECONDARY
  • Acquired metabolic aberrations

hypokaliemia, hypercalcemia

  • Drugs

lithium,αmphotericin Β,diphenylhydantoin,foscarnet,

cidofovir

  • Medullary damage

chronic pyelonephritis ,cystinosis, sickle cell disease

chronic renal failure, obstructive nephropathy,

infiltrative disease (leukemia,lymphoma,amyloidosis)

solute diuresis accumulation of organic or inorganic solutes in urine
SOLUTE DIURESIS(accumulation of organic or inorganicsolutes in urine)

Organic

  • Glycose (diabetes mellitus,

renal glycosuria)

  • Urea (large protein intake

increasedcatabolism

relief of obstruction)

  • Mannitol

Inorganic

  • Sodium chloride(diuretics,

mineralocorticoid deficiency

salt-losing renal diseases)

clinical evaluation
CLINICAL EVALUATION
  • Larger quantities of urine±dehydration

infancy -excessively heavy diapers

irritability, seizures

unexplained fever

constipation, vomiting

failure to thrive,mental retardation

children-polydipsia

enuresis, nocturia

  • non obstructive hydronephrosis ,hydroureter and megacystis by the large urinary volumes
diagnosis and differential diagnosis
DIAGNOSIS AND DIFFERENTIAL DIAGNOSIS
  • Onset of polyuria

Hereditary nephrogenic DI first week of life

Familial central DI after the first year of life

ADULTS Central DI abrupt onset

Aquired nephrogenic DI gradual onset

Primary polydipsia gradual onset

Onset of nocturia is often the first clue to DI

Relationship with CNS injury

  • Family history
  • Plasma sodium concentration
  • Presence of polyhydramnios
laboratory investigations
Laboratory Investigations
  • 24hour urine collection
  • Serum glycose,urea and creatinine
  • Κ, Ca, Na,biccarbonates
  • Urine(first morning) osmolality , urinalysis
  • Serum osmolality
  • Water restriction test
  • Test of dDAVP
  • Plasma ADH measurement
  • Genetic studies
osmoregulation of adh
Osmoregulation of ADH

The normal physiologic response is based upon the following observations:

  • Raising the plasma osmolality leads to a progressive elevation in ADH release and an increase in urine osmolality in normals
  • Once the plasma osmolality reaches 295 to 300 mOsmol/kg ,the effect of endogenous ADH on the kidney is maximal. At this point administering ADH

will no further elevate the urine osmolality unless endogenous ADH release is impaired (central DI)

water restriction test
WATER RESTRICTION TEST
  • Is not performed in newborns or very young infants
  • Is not performed when plasma Na>145 mEq/l
  • It should be performed in the hospital under medical supervision

The test is terminated when one of the end points are attained:

  • Urine SG> 1020or Urine osmolality > 600mOsm/kg ( infant ) 1015 >500
  • Plasma osmolality >295 mOsm/kg or plasma Na >147mEq/l
  • Loss of 5% of body weight or signs of volume depletion
  • Period of water restriction

6hours in infants < 6months of age

8 hours 6 months -2 years

12 hours >2 years

test ddavp
TEST dDAVP
  • Children who continue to have impaired urinary concentration despite reaching a plasma osmolality 295mosmol/kg or sodium of 150meq/L

5-10μg desmopressin by nasal insufflation(20μg/m2)

or 2,5-5U aqueous vasopressin subcutaneously

  • Accurate interpretation requires that exogenous ADH not givenbefore the plasma osmolality has reached 295 mosm/kg
  • Ifurineosmol.>100% complete central DI

15-50%partial central DI

partial nephrogenic DI

<10%complete nephrogenic DI

polyuria laboratory investigations
Polyuria- Laboratory Investigations

Plasma ADH measurement beforeand after water restriction test

  • NEPHROGENIC DI is excluded if there is an appropriaterelationship between the rise in urineosmolality andplasma ADH
  • CENTRAL DIis excluded if there is an appropriate rise in plasma ADH with the rise in plasma sodium or plasma osmolality
polyuria laboratory investigations31
Polyuria-Laboratory Investigations
  • Patients with central DI
  • MRI scans of pituitary gland, hypothalamus andsurrounding structures (serial)
  • Investigation of anterior pituitary hormonedeficits (GH,TSH,ACTH,FSH,LH)
  • Patients with nephrogenic DI
  • Renal ultrasound
  • Bladder function tests