Fluids and Electrolytes Flashcards
What is the effect of small bowel fistula on acid-base balance?
Small bowel fistula leads to normal anion gap metabolic acidosis.
What is the sodium concentration in 3% NS?
3% NS has 513 Na.
What is the normal serum osmolarity range?
Normal serum osmolarity is 280-295.
How is serum osmolarity calculated?
Serum osmolarity is calculated as 2XNa + glucose/18 + BUN/2.8.
What does high serum osmolarity indicate?
High serum osmolarity indicates dehydration or diabetes insipidus.
What does low serum osmolarity indicate?
Low serum osmolarity indicates fluid overload or SIADH.
What is the normal urine specific gravity range?
Normal urine specific gravity is 1.002 to 1.028.
What does high urine specific gravity suggest?
High urine specific gravity suggests dehydration or SIADH.
What does low urine specific gravity suggest?
Low urine specific gravity suggests fluid overload or diabetes insipidus.
What fluid is used for sweat fluid loss?
Normal saline is used for sweat fluid loss.
What fluid is used for saliva fluid loss?
1/2 NS with 20 K is used for saliva fluid loss.
What is the effect of small bowel and pancreatic juice loss?
It causes hyponatremic, hypokalemic non-anion gap metabolic acidosis.
What metabolic condition is caused by sweating?
Sweating causes hypernatremic metabolic acidosis.
What are the characteristics of diabetes insipidus?
Diabetes insipidus is characterized by hypernatremia, low urine sodium, high UOP, low specific gravity, and high serum sodium and osmolarity.
What can cause diabetes insipidus?
Diabetes insipidus can occur with ETOH or head injury.
What is the treatment for central diabetes insipidus?
The treatment for central diabetes insipidus is DDAVP.
What is the treatment for nephrogenic diabetes insipidus?
Nephrogenic diabetes insipidus is treated with a low salt diet, thiazide diuretic, and D5 water.
What are the characteristics of SIADH?
SIADH is characterized by hyponatremia, high urine sodium >20, low UOP, high urine specific gravity, high urine Na, and low serum Na and osmolarity.
What causes hyponatremia in SIADH?
High levels of ADH lead to natriuretic peptide release, causing sodium loss in urine.
- Can occur with head injury
What is the treatment for neurological symptoms in SIADH?
For neurological symptoms like seizure or lethargy, hypertonic saline is the treatment.
What is the initial treatment for mild symptoms of SIADH?
Fluid restriction is the initial treatment for mild symptoms of SIADH.
What is the treatment for SIADH due to brain injury?
For SIADH due to brain injury, 3% hypertonic saline is the treatment.
-fluid restriction can cause injury
What medications block ADH receptors in the kidney?
Conivaptan and demeclocycline block ADH receptors in the kidney.
What causes cerebral salt wasting?
Cerebral salt wasting is caused by excess release of atrial natriuretic peptide (released from right atrium)
What is the classic presentation of cerebral salt wasting?
Cerebral salt wasting is classically described as a patient with SAH, high urine output, and hyponatremic hypovolemia.
What is the key difference between SIADH and cerebral salt wasting?
The key difference is that in cerebral salt wasting, hyponatremia is caused by loss of sodium in urine, while in SIADH, it is due to water retention.
- Means that the only difference between the two is intravascular status
- CSW = Hypovolemic = key to diagnosis, while SIADH = Euvolemic or hypervolemic
What is the treatment for cerebral salt wasting?
The treatment for cerebral salt wasting is to replenish intravascular volume with normal saline.
What are the symptoms of hypercalcemia?
Hypercalcemia symptoms include nausea, vomiting, abdominal pain, AMS, ulcers, and kidney stones.
How is corrected calcium calculated?
Corrected calcium = Serum calcium + 0.8(4 - serum albumin).
What is the most common cause of hypercalcemia in outpatient settings?
The most common cause of hypercalcemia in outpatient settings is primary hyperparathyroidism (PHPT).
-in inpatient its cancer
What is the most common cancer causing hypercalcemia? What are other cancers that can cause hypercalcemia?
The most common cancer causing hypercalcemia is breast cancer. Other cancers include squamous cell lung cancer and multiple myeloma.
What are the PTH levels in cancer causing hypercalcemia?
PTH levels are low in cancer causing hypercalcemia.
What is the main mechanism of high calcium in cancer?
The main mechanism is elevated calcium due to PTHrP, which resorbs calcium in the kidney and causes bone destruction.
- Non-hematological malignancy: PTH-rp
- Hematologic malignancy: Cause bone destruction causes increase in Ca, MC multiple myeloma
What is the treatment for all hypercalcemia?
The treatment includes normal saline + bisphosphonate (zoledronic acid) as the initial treatment of choice.
What to use if a patient with hypercalcemia has renal failure?
If renal failure is present, denosumab is used to reduce osteoclast activity instead of bisphosphonates.
What are adjunct treatments for hypercalcemia?
Adjunct treatments include calcitonin, cinacalcet, and steroids.
When should steroids be given in hypercalcemia?
Steroids should be given for lymphoma secreting calcitriol.
What is the role of loop diuretics in hypercalcemia?
Loop diuretics have fallen out of favor as they worsen electrolytes.
What does cinacalcet do?
Cinacalcet decreases PTH production and is used in secondary hyperparathyroidism, ectopic PTH, and parathyroid cancer to decrease calcium.
Cinacalcet is not used in malignant hypercalcemia because PTH is suppressed.
What is the fluid production by saliva?
Saliva produces about 1500 ml.
What is the fluid production by the stomach?
The stomach produces about 1000-2000 ml.
What is the fluid production by the biliary system?
The biliary system produces about 500 ml.
What is the fluid production by pancreatic juice?
Pancreatic juice produces about 1500 ml.
What is the fluid production by the small bowel?
The small bowel produces about 1500 ml.
What is tumor lysis syndrome characterized by?
Tumor lysis syndrome is characterized by high uric acid, potassium, phosphate, and low calcium, along with metabolic lactic acidosis and AKI.
What should be avoided in tumor lysis syndrome?
Calcium should be avoided as it causes calcium-phosphate crystal deposition in the kidney, leading to renal injury.
What is the treatment for tumor lysis syndrome?
The treatment is hydration, and dialysis if refractory.
What is the most common cause of metabolic alkalosis?
The most common cause of metabolic alkalosis is contraction alkalosis (NGT to suction, vomiting, GOO, pyloric stenosis).
What do gastric losses cause in metabolic alkalosis?
Gastric losses cause low chloride and hydrogen, leading to hypochloremic alkalosis.
What is the treatment for metabolic alkalosis?
The treatment is fluid resuscitation with normal saline.
What are the two forms of metabolic alkalosis?
The two forms are chloride responsive alkalosis and chloride resistant alkalosis.
What characterizes chloride responsive alkalosis?
Chloride responsive alkalosis is characterized by temporary loss of chloride that can be replaced, with low chloride in urine <10.
- Examples: gastric loss, NGT, vomiting, diuretic use
- these you treat by giving NS
What characterizes chloride resistant alkalosis?
Chloride resistant alkalosis is characterized by hormonal mechanisms where chloride cannot be replaced, with high chloride in urine >20.
-Examples: Conn syndrome, secondary hyperaldosteronism, cushings
How is total free water deficit calculated for males?
Total free water deficit = 0.6 (male) × weight (kg) × [(Serum Na+/140) - 1].
How is total free water deficit calculated for females?
Total free water deficit = 0.5 (female) × weight (kg) × [(Serum Na+/140) - 1].
How much of the total free water deficit should be replaced in the next 24 hours?
Half of the total free water deficit should be replaced in the next 24 hours.
What is plasma osmolarity?
Plasma osmolarity = (2 X Na) + (glucose/18) + (BUN/2.8). Normal is 280-295.
What can cause pseudohyponatremia?
Hyperglycemia can cause pseudohyponatremia; for each 100 glucose over normal, add 2 Na.
What can cause pseudohypocalcemia?
Low albumin can cause pseudohypocalcemia; corrected calcium = Serum Ca + 0.8 × [4 - albumin].
For every 1 g of decrease in albumin, add 0.8 to Ca
What is the formula for anion gap?
Anion gap = Na - (HCO3 + Cl); normal is <12.
What is the delta anion gap used for?
Delta anion gap checks if CO2 responded appropriately in high anion gap metabolic acidosis.
- = (change in anion gap from normal – change in CO2 from normal)
- < 1 = also has Non-gap metabolic acidosis, >1 also has metabolic alkalosis
What does FeNa indicate?
FeNa = (Urine Na/Cr) / (Plasma Na/Cr); it helps assess kidney function.
What characterizes contrast-induced nephropathy?
Contrast-induced nephropathy is characterized by intrinsic kidney injury with FeNa <1%, normal UOP, rise in Cr, and muddy brown casts.
What do brown casts indicate?
Brown casts indicate acute tubular necrosis (ATN).
Paradoxical acuduria
Kidney reabsorbed Na in exchange for K. Na/K pump (aldosterone) hypokalemia
K/H exchanger in kidney absorbs K paradoxical aciduria
Tx: Fluid resuscitation with normal saline!!!
Acid-base abnormality associated with high ouput fistula/stoma
-Metabolic acidosis with a normal anion gap
-Normal anion gap because loos of HCO3- with compensatory increase in Cl-
-Hyperchloremic because negatively charged Cl- displaced to extracellular space with loss of bicarb
Metabolic acidosis in vomiting (gastric outlet obstruction, congenital hypertrophic pyloric stenosis)
Hypokalemic, hypchloremic metabolic alkalosis
Medical treatment of caclicum channel blocker toxicity
-IV calcium gluconate or chloride
-High-dose insuilin
-Atropine if bradycardic
-Norepinephrine if suspected vasodilatory shock
-Dobutamine or epinephrine if suspected cardiogenic shock
Intubate if GCS less than 8
