Complications of CKD Flashcards
What are the complications of CKD?
Accumulation of waste products
Salt and water retention
High blood pressure
Metabolic acidosis
Hormone disturbaces
Examples of hormonal disturbances triggered by CKD
Secondary hyperparathyroidism
Bone disease
Why does fluid accumulate in CKD?
The ability for the tubule to filter water and sodium breaks down
Water and salt retention leads to fluid accumulation
What are clinical ways to pick up fluid accumulation?
Press on skin - leaves dent due to presence of water
Pulmonary oedema - can hear crackles via stethoscope
How does CKD affect blood pressure?
CKD leads to secondary hypertension
Secondary hypertension causes more kidney injury
What causes secondary hypertension in CKD?
Fluid retention
Activation of the renin-angiotensin system
Excess renin production
Increased sympathetic activity
What are the consequences of hypertension?
Left ventricular hypertrophy
Heart failure - many patients with CKD die from heart failure rather than kidney failure
What is metabolic acidosis?
When kidney are not removing enough acids from the body, so there is a build up of acid in the blood
Why does CKD lead to metabolic acidosis?
There is diminished excretion of non-volatile acids
Increased loss of bicarbonate ions
What do patients with metabolic acidosis present wit clinically?
Hyperventilation
To remove the carbon dioxide from the system - pushes to form less carbonic acid
Which hormones do kidneys control?
EPO
Vitamin D
What stimulates EPO production from the kidney?
Decreased blood oxygen
What is the role of EPO?
Acts in the bone marrrow to increase numbers of RBC precursors
What happens to EPO production during CKD?
EPO concentration decreases
There is less RBC precursor production
Less RBC in the blood
What condition stems from the decreased EPO synthesis?
Normochromic normocytic anaemia
What does normochromic normocytic anaemia mean?
Normochromic - normal shape
Normocytic - normal size
The RBC are normal, there are just less produced than what is needed
How is vitamin D metabolised in the body?
Vitamin D is obtained from the gut or skin
FIrst it is hydroxylated in the liver to form 25(OH)D
Then it passes to the kidneys and is hydroxylated to 1,25(OH)2D - active form
What does PTH do?
Maintains bone turnover
What do patients with CKD have in context to PTH?
Secondary/ tertiary hyperthyroidism
What is the pathogenesis of secondary/ tertiary hyperthyroidism?
Kidneys diseases and becomes smaller
Therefore it releases less active form of vitamin D -> 1,25(OH)2D
Parathyroid gland has receptor for this molecule -> negative feedback loop
There is a compensatory increase in the PTH released
The parathyroid gland becomes hypertrophied and autonomous -> releases PTH regardless of stimulus
What is the condition called when the parathyroid gland releases PTH regardless of the stimulus?
Tertiary hyperthyroidism
What are the clinical presentations of hyperthyroidism?
Bone erosion
Bone fracturing
Hypercalcemia
What other hormone does the parathyroid release?
FGF23
What is FGF23?
A fibroblast growth factor
How does FGF23 affect 1,25-vitD levels?
Decreases the release of the vitamin D intermediate
What stimulus causes FGF23 to be released?
An increase in blood concentration of vitamin D active intermediate
An increase in phosphate concentration in the blood
How does CKD affect FGF23 release?
Inhibits reabsorption of phosphate from the urinary tract
Blood concentration of phosphate decreases
FGF decreases 1,25-vitD release - there is an increase in PTH release (negative feedback loop)
Phosphate also binds directly to receptors on the parathyroid - increases PTH release
