Nyresygdomme, salt og vandbalance Flashcards
Three Components of Urine Formation
Filtration (Glomerulus)
Reabsorption (Inner medulla, the loop of Henle)
Secretion
Antidiuretisk hormon
Gør nyrernes samlerør mere permeable overfor vand -> mere vand kan reabsorberes fra urin til blod -> blodets osmolaritet falder
Renal Calculi (nyresten) - Ætiologi
- Saturation theory: urine is supersaturated with stone components
- Matrix theory: organic materials act as a nidus for stone formation
- Inhibitor theory: a deficiency of substances that inhibit stone formation
Four types of kidney stones:
Calcium stones (i.e., oxalate or phosphate)
Magnesium ammonium phosphate stones
Uric acid stones
Cystine stones
Urinary Tract Infections - Patologi
Bacteria usually enter through the urethra
Host defenses include: Washout phenomenon Protective mucus Local immune responses and IgA Normal bacterial flora
Beer Drinkers Potomania
Beer drinkers eller fejlernærede
- beer contains little or no sodium, potassium, or protein, and the carbohydrate load will suppress endogenous protein breakdown and therefore urea excretion
Potomania
Normal subjects excrete 600 to 900 mosmol/kg of solute per day (primarily sodium and potassium salts and urea) (s-osmolaritet 280-300 mOsm/kg).
thus, if the minimum urine osmolality is 60 mosmol/kg, the maximum urine output will be 10 to 15 L/day (for example, 900 mosmol/day ÷ 60 mosmol/kg = 15 L).
Beer drinkers, daily solute excretion may fall below 250 mosmol/kg, leading to a reduction in the maximum urine output to below 4 L/day even though the urine is appropriately dilute. Hyponatremia will ensue if more than this amount of fluid is taken in.
Hyponatriæmi
Ubalance mellem vandindholdet og natriumindholdet i ekstracellulærvæsken
Hyponatriæmi - Årsager
Sygdomme hvor niveauet af AHD er forhøjet
Sygdomme hvor niveauet af ADH er passende undertrykt
Hyponatriæmi med normal eller forhøjet plasmaosmolaritet
ED evaluation hyponatraemia
2 goals: to determine the chronicity of the hyponatremic state and to determine the cause.
Acute hyponatremia is less common than chronic hyponatremia and typically is seen in patients with a history of sudden free water loading (eg, patients with psychogenic polydipsia, infants fed tap water for 1-2 days, patients given hypotonic fluids in the postoperative period).
The ultimate danger for these patients is brainstem herniation when sodium levels fall below 120 mEq/L.
The therapeutic goal is to increase serum sodium rapidly by 4-6 mEq/L over the first 1-2 hours.
First, the source of free water must be identified and eliminated.
ED evaluation hyponatraemia 2
In patients with healthy renal function and mild to moderately severe symptoms, serum sodium may correct spontaneously without further intervention.
Patients with seizures, severe confusion, coma, or signs of brainstem herniation should receive hypertonic (3%) saline to rapidly correct serum sodium toward normal, but only enough to arrest the progression of symptoms.
An increase in serum sodium of 4-6 mEq/L is generally sufficient.
ED evaluation hyponatraemia 3
Chronic hyponatremia is more common than acute hyponatremia.
These patients lack any history of sudden free water loading.
The risk of CPM appears to be minimal in patients whose chronic hyponatremia is corrected at a rate of less than 0.5 mEq/L/hour or 12 mEq/L/day.
(Anecdotal reports suggest that therapeutic relowering of the serum sodium with hypotonic fluids and desmopressin (DDAVP) may help avert neurologic sequelae in patients whose chronic hyponatremia is inadvertently corrected too quickly.)
ED evaluation hyponatraemia 4
cause of the hyponatremic state
Hypovolemic hyponatremia: Patients have decreased total body sodium stores. If symptoms are mild to moderately severe, treat with isotonic saline; monitor serum sodium levels frequently to ensure that serum sodium increases no faster than 0.5 mEq/L/hour or 12 mEq/L/day.
Hypervolemic hyponatremia: Patients have increased total body sodium stores. Treatment consists of sodium and water restriction and attention to the underlying cause.
Euvolemic hyponatremia: This implies normal sodium stores and a total body excess of free water. Treatment consists of free water restriction and correction of the underlying condition.
ED evaluation hyponatraemia 5
Complications related to hyponatremia include rhabdomyolysis, seizures, permanent neurologic sequelae related to ongoing seizures or cerebral edema, respiratory arrest, and death.
Complications related to therapy of hyponatremia include fluid overload and CPM.
Blood K+ Levels Control Resting Potential (cont.) - Hypokalemia
lowers resting potential away from threshold
Cells fire less easily
Blood K+ Levels Control Resting Potential - Hyperkalemia
raises resting potential toward threshold
Cells fire more easily
When resting potential reaches threshold, Na+ gates open and won’t close
