Central diabetes insipidus impact on uric acid metabolism, lipid profile, electrolytes and serum cortisol

الملخص EN

Diabetes insipidus is a rare clinical syndrome, which can occur in one of two forms: central diabetes insipidus or nephrogenic diabetes insipidus.

Diagnosis of the etiology and differentiation between the different forms are essential for both therapy and follow up of cases.

Central diabetes insipidus does not only affect water metabolism but it also affects other body parameters.

The aim of the work : To study the impact of central diabetes insipidus on uric acid metabolism, lipid profile, serum sodium, potassium and Cortisol.

To evaluate the increase in serum uric acid as a tool to diagnose central diabetes insipidus (CDI) and if this hyperuricemia is due to an increase in endogenous urate.

Last the use of magnetic resonance imaging (MRI) in the diagnosis and the findingjf possible to study etiological factors of central diabetes insipidus.

Subjects and Methods : Twenty patients with polyurea and polydipsia and twelve healthy controls (Group 1) were included in this study.

Eight patients were excluded after performing water deprivation test and the rest twelve confirmed to have central diabetes insipidus represented (Group 2).

All subjects included in Group 1 and Group 2 were subjected to the following : Thorough history taking and clinical examination.

Laboratory investigations deluding : complete urine analysis, kidney function tests, serum uric acid,24 hours urinary uric acid, serum sodium and potassium, lipid profile and morning serum Cortisol.

Magnetic resonance imaging (TiWI) on posterior pituitary and pituitary stalk was only done to the patients.

Results : A significant rise in serum uric acid was seen in patients with CDI when compared to controls (p < 0.01) and this rise persisted even after administration of vasopressin (AVP).

On the other hand, no significant rise was found in the 24 hours urinary uric acid (p>0.05) comparing the two groups.

Also, we observed a non-significant decrease in morning serum Cortisol (p > 0.05).

A significant increase in serum triacylglycerol (p < 0.05), total cholesterol (p < 0.001) and LDL-choIesteroI (p < 0.001) with a significant reduction in HDL-cholesterol (p < 0.01) were found in patients with CDI when compared to controls.

On the other hand, diere was no significant change in these parameters in patients with CDI before and after therapy.

Magnetic resonance imaging showed only the loss of the normal hyperintense (bright) shadow or signal of the posterior pituitary with no other etiological lesion in most of the patients included in this study.

Conclusion : We conclude that hyperuricemia in polyuric, polydepsic patients is highly suggestive of CDI (a fact which is not attributed to an increase in endogenous urates but most probably is due to a lack of Vi receptor stimulation).

We shed light on possible dislipidemia associated with CDI for follow up and treatment if needed.

Last MRI is another useful tool for evaluation of the functional status of neurohypophyseal system in idiopathic CDI, still it may fail to uncover an underlying etiology.