Diabetes insipidus
Introduction
Diabetes means "run right through." Diabetes insipidus reflects that the kidney is unable to concentrate urine and excreted hypotonic relative to plasma as antidiuretic hormone (ADH) is not working properly in incorporating water channels luminal in manifold. Manifold tubes is therefore impermeable to water. Loss of water through the urine can become very large, over 20 liters per day. Causes
We distinguish between nephrogenic and neurogenic diabetes insipidus. By neurogenic diabetes insipidus is there a lack of ADH due to illness / injury in the pituitary / hypothalamus. When nephrogenic diabetes insipidus ADH produced normally, but the hormone does not work properly due to illness / injury to the tubular cells. Table of common causes of diabetes insipidus
| Causes | Examples |
|---|
| Renal diabetes insipidus | Medications |
| Lithium, demeclocycline, amphotericin B ++ |
| Hypercalcemia |
| Hypokalemia |
| Obstructive nephropathy |
| Congenital gene mutations |
| Neurogenic diabetes insipidus | Hypofysekirurgi |
| Head Trauma |
| Pituitary tumor |
| Vascular disaster |
| Infections |
| Sarcoidosis |
| Autoimmune |
| Congenital gene mutations |
Clinical presentation
Diabetes insipidus present with polyuria, thirst and polyuria. Diabetes insipidus may present themselves in complete or partial form. Fluid loss can be very large by complete disappearance of ADH, and if the patient fails to compensate the loss can be severe dehydration quickly. Hypernatraemia and hypokalemia caused by aldosterone activation resulting from activation of the renin-angiotensin system (RAS). At relative ADH deficiency or renal diabetes insipidus with slightly reduced ADH response, the diagnosis may be difficult to detect. Diagnosis is confirmed by measuring the low urinary osmolality despite high plasmaosmolalitet after a period of thirst. Course and treatment
Upon complete form, the condition is life-threatening because of the risk of dehydration and elektrolytforstyrrelser. Putting the underlying cause is necessary. Neurogenic diabetes insipidus can be treated with infusion of ADH as nasal spray or iv. When nephrogenic diabetes insipidus, external supply of the hormone has no effect. Precipitating cause must be removed. Low salt and low protein diet will cause less diuresis in patients with nephrogenic diabetes insipidus.
Some diuretics may paradoxically virkepositivt of polyuria in diabetes insipidus. Thiazide diuretics combined with salt diet gives a mild hypovolemia increasing proximal reabsorption and decreases urine volume to the ADH sensitive areas distal nephrons and limiting polyuria.
Amiloridbehandling may be beneficial in combination with thiazides by acting synergistically through the same mechanism. In addition, amiloride be especially advantageous for lithium-induced diabetes insipidus, when the drug is blocking Na channels luminal in manifold. Lithium enters cells through these channels and affect ADH response in cells, amiloride counteracts therefore this side effect of lithium. Loop diuretics are not suitable for limiting polyuria.
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