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Diabetes incipidus

Lab test and diagnostic

Water deprivation test. This test helps determine the cause of diabetes insipidus. You'llbe asked to stop drinking fluids two to three hours before the test so that your doctor canmeasure changes in your body weight, urine output and urine composition when fluids

are withheld. Your doctor may also measure blood levels of ADH during this test. The

water deprivation test is performed under close supervision in children and pregnant

women to make sure no more than 5 percent of body weight is lost during the test.

Urinalysis. Urinalysis is the physical and chemical examination of urine. If your urine isless concentrated (meaning the amount of water excreted is high and the salt and waste

concentrations are low), it could be due to diabetes insipidus.

Magnetic resonance imaging (MRI). An MRI of the head is a noninvasive procedurethat uses a powerful magnet and radio waves to construct detailed pictures of brain

tissues. Your doctor may want to perform an MRI to look for abnormalities in or near the

pituitary gland.

Genetic screeningIf your doctor suspects an inherited form of diabetes insipidus, he or she will look at your familyhistory of polyuria and may suggest genetic screening.

Hyperparathyroidism

Symptoms

Back pain

Blurred vision (because of cataracts ) Bone pain or tenderness Decreased height Depression Fatigue Fractures of long bones Increased urine output Increased thirst Itchy skin Joint pain Loss of appetite Nausea Muscle weakness and pain Personality changes Stupor and possibly coma Upper abdominal pain

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Signs and tests

Blood tests will be done to check for increased levels of parathyroid hormone (PTH), calcium,

and alkaline phosphatase, and lower levels of phosphorus. A 24-hour urine collection test can

help determine how much calcium is being removed from the body.

Bone x-rays and bone mineral density test can help detect bone loss, fractures, or bone softening.

X-rays, ultrasound, or CT scans of the kidneys or urinary tract may show calcium deposits or ablockage.

Diabetes incipidus

Electrolyte and volumehomeostasisis a complex mechanism that balances the body's

requirements forblood pressureand the main electrolytessodiumandpotassium. In general,

electrolyte regulation precedes volume regulation. When the volume is severely depleted,however, the body will retain water at the expense of deranging electrolyte levels.

The regulation of urine production occurs in thehypothalamus, which producesADHin the

supraopticandparaventricularnuclei. After synthesis, the hormone is transported in

neurosecretory granules down the axon of the hypothalamic neuron to the posterior lobe of thepituitary glandwhere it is stored for later release. In addition, the hypothalamus regulates thesensation of thirst in theventromedial nucleusby sensing increases in serum osmolarity and

relaying this information to thecortex.

The main effector organ forfluidhomeostasis is thekidney. ADH acts by increasing water

permeability in thecollecting ductsand distal convoluted tubules, specifically it acts on proteinscalledaquaporinsand more specifically aquaporin 2 in the following cascade; ADH (akaargenine vasopressin-AVP) produced in the hypothalmus and stored in the posterior pituitary.

When released, ADH binds to V2 G-protein coupled receptors within the distal convoluted

tubules, increasingcyclic AMP, which couples withprotein kinase Astimulating transcription ofthe aquaporin 2 channel stored in thecytoplasmof the distal convoluted tubules and collecting

ducts into the apical membrane. These transcripted channels allow water into the collecting duct

cells. The increase in permeability allows for reabsorption of water into the bloodstream, thus

concentrating the urine.

Hereditary forms of diabetes insipidus account for less than 10% of the cases of diabetes

insipidus seen in clinical practice

http://en.wikipedia.org/wiki/Homeostasishttp://en.wikipedia.org/wiki/Homeostasishttp://en.wikipedia.org/wiki/Homeostasishttp://en.wikipedia.org/wiki/Blood_pressurehttp://en.wikipedia.org/wiki/Blood_pressurehttp://en.wikipedia.org/wiki/Blood_pressurehttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Potassiumhttp://en.wikipedia.org/wiki/Potassiumhttp://en.wikipedia.org/wiki/Potassiumhttp://en.wikipedia.org/wiki/Hypothalamushttp://en.wikipedia.org/wiki/Hypothalamushttp://en.wikipedia.org/wiki/Hypothalamushttp://en.wikipedia.org/wiki/ADHhttp://en.wikipedia.org/wiki/ADHhttp://en.wikipedia.org/wiki/ADHhttp://en.wikipedia.org/wiki/Supraoptic_nucleushttp://en.wikipedia.org/wiki/Supraoptic_nucleushttp://en.wikipedia.org/wiki/Paraventricular_nucleushttp://en.wikipedia.org/wiki/Paraventricular_nucleushttp://en.wikipedia.org/wiki/Paraventricular_nucleushttp://en.wikipedia.org/wiki/Pituitary_glandhttp://en.wikipedia.org/wiki/Pituitary_glandhttp://en.wikipedia.org/wiki/Ventromedial_nucleushttp://en.wikipedia.org/wiki/Ventromedial_nucleushttp://en.wikipedia.org/wiki/Ventromedial_nucleushttp://en.wikipedia.org/wiki/Cerebral_cortexhttp://en.wikipedia.org/wiki/Cerebral_cortexhttp://en.wikipedia.org/wiki/Cerebral_cortexhttp://en.wikipedia.org/wiki/Body_waterhttp://en.wikipedia.org/wiki/Body_waterhttp://en.wikipedia.org/wiki/Body_waterhttp://en.wikipedia.org/wiki/Kidneyhttp://en.wikipedia.org/wiki/Kidneyhttp://en.wikipedia.org/wiki/Kidneyhttp://en.wikipedia.org/wiki/Collecting_ductshttp://en.wikipedia.org/wiki/Collecting_ductshttp://en.wikipedia.org/wiki/Collecting_ductshttp://en.wikipedia.org/wiki/Aquaporinhttp://en.wikipedia.org/wiki/Aquaporinhttp://en.wikipedia.org/wiki/Aquaporinhttp://en.wikipedia.org/wiki/Cyclic_AMPhttp://en.wikipedia.org/wiki/Cyclic_AMPhttp://en.wikipedia.org/wiki/Cyclic_AMPhttp://en.wikipedia.org/wiki/Protein_kinase_Ahttp://en.wikipedia.org/wiki/Protein_kinase_Ahttp://en.wikipedia.org/wiki/Protein_kinase_Ahttp://en.wikipedia.org/wiki/Cytoplasmhttp://en.wikipedia.org/wiki/Cytoplasmhttp://en.wikipedia.org/wiki/Cytoplasmhttp://en.wikipedia.org/wiki/Cytoplasmhttp://en.wikipedia.org/wiki/Protein_kinase_Ahttp://en.wikipedia.org/wiki/Cyclic_AMPhttp://en.wikipedia.org/wiki/Aquaporinhttp://en.wikipedia.org/wiki/Collecting_ductshttp://en.wikipedia.org/wiki/Kidneyhttp://en.wikipedia.org/wiki/Body_waterhttp://en.wikipedia.org/wiki/Cerebral_cortexhttp://en.wikipedia.org/wiki/Ventromedial_nucleushttp://en.wikipedia.org/wiki/Pituitary_glandhttp://en.wikipedia.org/wiki/Paraventricular_nucleushttp://en.wikipedia.org/wiki/Supraoptic_nucleushttp://en.wikipedia.org/wiki/ADHhttp://en.wikipedia.org/wiki/Hypothalamushttp://en.wikipedia.org/wiki/Potassiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Blood_pressurehttp://en.wikipedia.org/wiki/Homeostasis

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