Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

severe hyponatraemia (<125 mmol/L [<125 mEq/L]) or with neurological symptoms

1st line – hypertonic (3%) saline infusion plus frequent monitoring

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ACUTE
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severe hyponatraemia (<125 mmol/L [<125 mEq/L]) or with neurological symptoms
1st line – 

hypertonic (3%) saline infusion plus frequent monitoring

Neurological symptoms (including restlessness, psychosis, ataxia, stupor, and coma) are predominant at serum sodium levels <125 mmol/L (<125 mEq/L).[54] An acute drop in sodium level of 10 mmol/L (10 mEq/L) over a few hours may be sufficient to produce clinical symptoms, including restlessness, salivation, ataxia, stupor, and coma.[67]

Rapid correction with hypertonic saline (3%) infusions is needed. Infusion rates range from 1 mL/kg/hour up to 6 mL/kg/hour if severe neurological symptoms such as seizures are present.[41] Correction should continue until the patient is asymptomatic and serum sodium level is >118-120 mmol/L (>118-120 mEq/L), to minimise the risk of seizures. Once the patient is asymptomatic and sodium levels are >118 mmol/L (>118 mEq/L), correction should occur at a maximum of 8 mmol/L (8 mEq/L) in 24 hours, to achieve a target sodium level of 125 mmol/L (125 mEq/L).[68]

Close and frequent monitoring of serum sodium and electrolytes is mandatory until sodium levels increase and symptoms subside.[65] Electrolytes should be monitored initially every 2-3 hours, progressing to every 6-12 hours when sodium levels stabilise.[65] This minimises the risk of central pontine myelinolysis and osmotic demyelination, which can occur with very rapid correction.[1]

hyponatraemia (125-130 mmol/L [125-130 mEq/L]) or with GI symptoms

1st line – hypertonic (3%) saline infusion plus frequent monitoring

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ACUTE
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hyponatraemia (125-130 mmol/L [125-130 mEq/L]) or with GI symptoms
1st line – 

hypertonic (3%) saline infusion plus frequent monitoring

Gastrointestinal symptoms (including nausea and vomiting) can be seen in patients with sodium levels between 125 and 130 mmol/L (125-130 mEq/L).[54]

Correction of the sodium deficit with hypertonic saline (3%) infusions is needed. The goal is to limit correction to <12 mmol/L (<12 mEq/L) (1.5 to 2 mEq/L/hour or approximately 0.5 mmol/L/hour) on the first day and <6 mmol/L (<6 mEq/L) for every subsequent day until symptoms subside or serum sodium rises. Symptoms usually subside after a modest increase in sodium of 3-5 mmol/L (3-5 mEq/L).[29]

Close and frequent monitoring of serum sodium and electrolytes is mandatory until sodium levels increase and symptoms subside.[65]

ONGOING

chronic polydipsia

1st line – fluid restriction

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ONGOING
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chronic polydipsia
1st line – 

fluid restriction

Patients with chronic symptoms and no or mild hyponatraemia should be treated with fluid restriction. For those with dilute urine (urine osmolality <200 mOsm/kg H₂O), fluid restriction should begin at 1 to 1.5 L/day. However, for patients with urine osmolality >200 mOsm/kg H₂O, fluid restriction to 0.8 to 1.5L/day is recommended.[29] Fluid restriction necessitates constant monitoring to prevent patients from seeking alternative water sources (e.g., bathroom taps).

Regular patient weights are often used to determine water intake diurnally. In a monitored setting (e.g., in a hospital or group home), patients may be weighed each morning and in the afternoon, as well as any time they are showing symptoms of polydipsia.[10] If body weight exceeds a pre-determined threshold, brief fluid restriction for 1-3 hours may help eliminate excess water through diuresis.[10] Differences in diurnal weight gain in patients with PPD can be much greater than those in controls (2.2% vs. 0.6%).[37]

Consider – furosemide

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ONGOING
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chronic polydipsia
Consider – 

furosemide

Additional treatment recommended for SOME patients in selected patient group

Concomitantly giving loop diuretics (e.g., furosemide) to enhance water excretion may be necessary. This has been described in individuals with intellectual disabilities and behavioral disorders in the intensive care setting.[69] 

Furosemide preferentially causes water excretion over sodium excretion.[1]

Primary options

furosemide: 20-40 mg intravenously once daily

Consider – behavioural therapy

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ONGOING
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chronic polydipsia
Consider – 

behavioural therapy

Additional treatment recommended for SOME patients in selected patient group

As non-compliance rates for therapeutic fluid restriction are high in patients with psychiatric disorders, behavioural intervention and modification are often necessary.

Group psychotherapy may improve adherence to fluid restriction.[70]

Reinforcement schedules using tokens for rewards or removing tokens for non-adherence have also been used with some success.[71]

Cognitive techniques to address thoughts leading to drinking behaviour, by implementing a behavioural programme to restrict water intake, can be used. Patients are followed up weekly for 12 weeks. The focus is on stimulus-control methods that include positive reinforcement and coping skills (substituting ice cubes for drinks, taking small sips, engaging in distracting activities). Delusions and fears related to drinking excessively are addressed. The patient maintains a log of the time, fluid amount, and mitigating situation for each beverage consumed.[49]

Most behavioural intervention studies are reported in inpatients, often requiring close monitoring and a substantial time commitment from staff. In extreme cases of non-adherence, patients may be confined to an area where there are no water sources.

Consider – psychopharmacotherapy

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ONGOING
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chronic polydipsia
Consider – 

psychopharmacotherapy

Additional treatment recommended for SOME patients in selected patient group

Atypical antipsychotics have been reported to have some success in improving symptoms of PPD.[75]

Clozapine has shown benefit in case reports and prospective trials.[1][10][72][73] A prospective 6-week study of clozapine in 8 patients with schizophrenia who had polydipsia and low plasma osmolality showed that clozapine normalised plasma osmolality and was well tolerated.[74] However, PPD is not a licensed indication for clozapine, and although clozapine has the most evidence for antipsychotic use in PPD, the use of clozapine and presence of hyponatraemia are both associated with a decreased seizure threshold. Therefore, this potential iatrogenic effect should be considered in clinical decision-making, especially when other comorbidities which increase the risk for epilepsy are present (e.g., traumatic brain injury, cerebrovascular accident).  

Other agents that may be considered include risperidone and olanzapine. Risperidone and olanzapine improved polydipsia in case reports, but prospective double-blind studies have not shown any benefit with olanzapine.[75][76][77]

Primary options

clozapine: consult specialist for guidance on dose

Secondary options

risperidone: consult specialist for guidance on dose

Tertiary options

olanzapine: consult specialist for guidance on dose

Consider – management of associated psychiatric condition

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ONGOING
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chronic polydipsia
Consider – 

management of associated psychiatric condition

Additional treatment recommended for SOME patients in selected patient group

The underlying psychiatric condition associated with PPD should be treated.[3]

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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