hyper nat re mia ppt

8/8/2019 Hyper Nat Re Mia Ppt

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HYPERNATREMIAHYPERNATREMIA


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Patient Case Review

HYPERNATREMIA


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Patient Case Review

HYPERNATREMIA


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Serum sodium level >150 clinicallysignificant

1% of hospitalised patients >60 yearsand up to 60% of febrile nursing homeresidents suffer from hypernatremia

Presence of hypernatremia isassociated with mortality rate of >40%;two thirds of survivors haveneurological sequelae

Mortality rate highest in elderly patientswith rapid onset hypernatremia andNa>160 (75% mortality)

Hypernatremia occurs in the setting ofserious disease, so high mortality ratesmay be a reflection of underlyingdisease rather than the hypernatremia

HYPERNATREMIA


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Plasma OsmolalityPlasma Osmolality

(280(280--290 mosmol/kg water)290 mosmol/kg water)

Physiological Relationship between Plasma Osmolality and

Hypernatremia

Increase?Increase?

Stimulation of theStimulation of the

thirst axis leadingthirst axis leading

to ADH releaseto ADH release

Direct stimulationDirect stimulation

of ADHof ADH

release from therelease from the

neurohypophysisneurohypophysis

ConcentratedConcentrated

UrineUrine

Total body water maintained

by ADH, renal handling of

solute and water and an

intact thirst mechanism.

If the urine is inadequately

concentrated or if inordinate

amounts of hypotonic fluid

are lost and/or not

replenished, hypernatremia

results. Thirst is an importantback up defence.


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Plasma OsmolalityPlasma Osmolality

(280(280--290 mosmol/kg water)290 mosmol/kg water)

Increase?Increase?

Stimulation of theStimulation of the

thirst axis leadingthirst axis leading

to ADH releaseto ADH release

Direct stimulationDirect stimulation

of ADHof ADH

release from therelease from the

neurohypophysisneurohypophysis

ConcentratedConcentrated

UrineUrine

Physiological Changes in the Elderly contributing to Hypernatremia

Decline in glomerular filtration rateImpaired ability to maintain water and

sodium homeostasis in response to

environmental and dietary changes

Total body water diminishes with age

A healthy elderly person can attain a

maximum urine osmolality of 700-800mosm/kg compared to a young adult

(1200 mosm/kg)

Diminished sensitivity to thirst in theelderly, predisposing to water deficiency

and hypernatremia

Tumours of the neurohypophysis,

granulamatous diseases, vascular insults

and metabolic disturbances can lead to

ADH deficiency.

Impaired ability to excrete a sodium load

due to age related reduction in end organ

responsiveness to ANP


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Diagnostic Algorithm for HypernatremiaAssess theAssess the

VOLUME STATUSVOLUME STATUS

of the patientof the patient

HYPO volaemia?HYPO volaemia?

Total body water very lowTotal body water very low

Total body sodium lowTotal body sodium low

EU volaemia?EU volaemia?

Total body water lowTotal body water low

Total body sodium normalTotal body sodium normal

HYPER volaemia?HYPER volaemia?

Total body water highTotal body water high

Total body sodium very highTotal body sodium very high

Measure Urine OsmolalityMeasure Urine Osmolality

U[Na]>20U[Na]>20 U[Na] 20

Renal LossesRenal Losses

-- DiureticsDiuretics

-- Intrinsic RenalIntrinsic Renal

DiseaseDisease

-- PostPost--

obstructionobstruction

ExtrarenalExtrarenal

LossesLosses

-- BurnsBurns

-- DiarrhoeaDiarrhoea

-- FistulaeFistulae

-- SweatingSweating

Renal LossesRenal Losses

-- DiabetesDiabetes

InsipidusInsipidus

-- HypodipsiaHypodipsia

ExtrarenalExtrarenalLossesLosses

-- InsensibleInsensible

losseslosses

-- RespiratoryRespiratory

-- DermalDermal

Sodium GainSodium Gain

-- HyperaldosHyperaldos--

teronismteronism

-- CushingsCushings

--HypertonicHypertonic

fluids/dialysisfluids/dialysis


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Diagnosing Hypernatremia

Common symptoms : lethargy, weakness, stupor, coma, seizures,muscle twitching, hyperreflexia, laboured respiration; check volumestatus

Cause of high Na is evident from history (e.g., burns, sweating,diuretics, renal disease, iatrogenic, hyperventilation, etc.)

If cause is unclear, measure plasma osmolality and urine sodiumconcentration (refer to handout)

Polyuria and polydipsia suggests diabetes insipidus as a cause ofhypernatremia; if this is the case, investigate for central vs.nephrogenic diabetes insipidus


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Hypovolaemic Hyponatremia

Patient loses both Na & water, but water loss>Na

loss

Check for signs of hypovolaemia : orthostatic

hypotension, tachycardia, flat neck veins,

skin turgor, dry mucous membranes

TBNa is low + hypotension Treat initially with

isotonic saline to replace sodium and water.

Thereafter, manage with 0.45% NaCl or 5%

dextrose solution to correct water deficit.

Treat causes of volume loss


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Euvolaemic Hyponatremia

Renal water loss leading to euvolaemichypernatremia is usually due to either a defect

in ADH production/release (central diabetes insipidus)

or failure of the collecting duct to respond to

ADH(nephrogenic).

Water loss >> Na loss. Mainstay of therapy is

5% dextrose. To correct the hypernatremia

appropriately, the TBW deficit must be estimated and

replaced as necessary.

Central diabetes insipidus : Treat with intranasaldesmopressin spray or desmopressin tablets

Nephrogenic diabetes insipidus : Remove the

precipitating drug, consider a thiazide diuretic and

NSAID.


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Hypervolaemic Hyponatremia

Least common form

Due to administration of hypertonic salinesolutions, sodium hydrogen carbonate fortreatment of metabolic acidosis, hyperkalemiaand dialysis against sodium dialysate.

Goal is to remove excess sodium usingdiuretics and 5% dextrose. Renal impairmentmay indicate need for dialysis.

Discontinue the offending drug(s)


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Management of Mrs. JM


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Summary

Sodium disorders are common, particularly in hospitalised elderly patients.

Mild sodium disorders are asymptomatic and self limiting. However, severe sodiumdisorders can cause significant morbidity and mortality.

The most common cause of sodium imbalance is iatrogenic, so a good medication reviewis often all that is required to correct the abnormality.

The key to diagnosing sodium disorders is assessment of the hydration status. Plasma andurine osmolality are key to diagnosing the cause of the imbalance.

Cause of hypernatremia usually obvious from history

Very little evidence from randomised controlled trials for the treatment of sodium disorders.

hyper nat re mia ppt

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