Symptoms of Inappropriate Anti-Diuretic Hormone

Question 1

SIADH

Answer 1

ADH (ant-diuretic hormone) controls water retention in the body

Also contstricts blood vessels

More ADH in body the more fluid you retain

Less ADH the more fluid you excrete

ADH works on distal con tub and collecting duct

Question 2

SIADH

Plasma Osmolality

If drink water water in blood increases and plasma osmolality drops

So hypothalamus detects this and tells pituitary to reduce ADH

More water is then excreted in urine

Therefore plasma osmolality back to normal

Answer 2

If ADH continues to be released even though plasma osmolality has dropped

Will continue to retatin water

As more water is retained other solutes are diluted eg Na

Fluid takes up more space causing Aldosterone to stop being released

Less aldosterone causes body to dump Na from blood into the urine

Concentration gradient cause water to follow Na, getting xs water being excreted with Na, normalising fluid volume in blood

Body is removing Na from an already low concentration

Plasma osmolality drops causing SIADH

Question 3

SIADH

Four different types

Answer 3

Symptoms:

Question 4

SIADH

Diagnosis

Answer 4

Symptoms and lab results:

Low body sodium and low osmolality plus high sodium and high osmolality in urine

Question 5

SIADH

Causes

Answer 5

Anything affection ADH:

• strokes
• haemorrhages
• trauma
• Drugs: mood stabilisers/anti-epileptics
• surgery
• tumours (small cell carcinoma in the lungs)
• infection in lungs and brain

Question 6

SIADH

Treatment

Answer 6