From the Guidelines
Amiloride is the preferred diuretic for treating lithium-induced nephrogenic diabetes insipidus (NDI). The typical dosage is 5-10 mg daily, which can be adjusted based on clinical response 1. Unlike thiazide diuretics which are also sometimes used, amiloride has the advantage of not increasing lithium levels, making it safer for patients who need to continue lithium therapy. Amiloride works by blocking sodium channels in the collecting ducts of the kidney, which reduces the gradient needed for water reabsorption and paradoxically decreases urine output in NDI. This helps alleviate symptoms like polyuria, polydipsia, and dehydration.
Other management strategies should include:
- Ensuring adequate fluid intake to prevent dehydration
- Reducing sodium intake which can worsen the condition
- Considering a reduction in lithium dosage if clinically appropriate If amiloride alone is insufficient, it can be combined with a low-dose thiazide diuretic, but this requires careful monitoring of lithium levels and electrolytes 1. It is essential to note that the use of diuretics in NDI should be tailored to the individual patient's needs and response, and regular follow-up is necessary to adjust treatment as needed.
In terms of emergency management, hypernatraemic dehydration is a common complication in NDI, and treatment should focus on correcting water deficiency with fluids that do not exacerbate the condition, such as water with dextrose 1. The choice of diuretic and management strategy should prioritize minimizing morbidity, mortality, and improving quality of life for patients with lithium-induced NDI.
From the Research
Diuretics Used to Treat Lithium-Induced Nephrogenic Diabetes Insipidus (NDI)
- Thiazide diuretics, such as hydrochlorothiazide, are commonly used to treat lithium-induced NDI, as they can reduce polyuria by increasing sodium and water uptake in proximal tubules 2.
- Amiloride is another diuretic that can be used to treat lithium-induced NDI, as it can reduce lithium-induced polyuria without affecting lithium or potassium levels 3.
- Nonsteroidal anti-inflammatory drugs (NSAIDs), such as indomethacin, have also been shown to be effective in reducing polyuria in patients with lithium-induced NDI 4, 5.
- The combination of thiazide diuretics, amiloride, and NSAIDs may be more effective in reducing polyuria than any single treatment alone 6.
Mechanism of Action
- Thiazide diuretics, such as hydrochlorothiazide, may exert an antidiuretic effect in lithium-induced NDI independently of the sodium-chloride cotransporter, possibly through a tubuloglomerular feedback response-mediated reduction in glomerular filtration rate due to proximal tubular carbonic anhydrase inhibition 2.
- NSAIDs, such as indomethacin, may reduce polyuria in lithium-induced NDI by decreasing renal prostaglandin synthesis, which can lead to an increase in water reabsorption in the collecting ducts 4, 5.