Diabetes insipidus is a condition which occurs due to deficiency of antidiuretic hormone(ADH) or inability of kidney to respond to normal levels of ADH,resulting in polyuria of very dilute urine,with polydipsia.
Cause of Diabetes insipidus is divided into
- Central(neurogenic) diabetes insipidus(CDI)
- Nephrogenic Diabetes insipidus(NDI).
Causes of central(neurogenic) diabetes insipidus(CDI) are
- Familial manisfested as autosomal dominant.
- Associated with diabetes mellitus,optic atrophy,nerve deafness,bladder atony.
- Acquired-idiopathic,tumour eg craniopharyngioma,inflammatory eg basal meningitis,head trauma,surgery causing disruption of pituitary stalk,irradiation,sheehan’s syndrome.
- Causes of nephrogenic Diabetes insipidus(NDI) are
- Familial-manifested as sex-linked recessive. Acquired-iatrogenic eg methoxyflurane,colchicine;after pyelonephritis,polycystic kidney disease,obstructive uropathy,hypokalaemia,hypercalcaemia,sickle cell anaemia.
PATHOLOGY BEHIND DIABETES INSIPIDUS:
Inappropriate ADH secretion implies persisitent release of ADH as consequences ,there is excess reabsorption of water in kidneys,expansion of extracellular fluid volume,which leads to haemodilution,hyponatramia,inability to excrete dilute urine.
In CDI,complete or partial deficiency results in polyuric statew,in which,in which kidneys is unable to concentrate urine,which results into large amount of dilute urine excretion.
In NDI,ADH production is normal,thre is ineffectual response of ADH on distal tubule or collecting tubule. the defect is in respond to ADH by kidney.
Clinically diabetes insipidus is characterised by two very important symptoms that is polyuria(increased frequency of micturation) and polydipsia.
polydipsia is consequence of polyuria that is to say polydipsia is compensatory mechanism to prevent dehydration by excessive incessant thirst,craving for ice cold water,disturbs sleep,patient may consume in excess of 10 litres of water per day,attempts to limit fluid intake my cause severe dehydration.
other features of diabetes insipidus are weakness,fatigue,irritability,muscular pains,constipation.
Look of diabetes insipidus patient-sunken eyes,drowsiness,dry skin,dry tongue,emaciation in prolonged cases.
- Severe dehydration,shock,coma,with or without convulsions.
Maintain fluid,electrolyte balance,eat well balanced,nutritious diet,consult a physician as early as possible.