Fluid and Electrolytes Ca and PO4^-3 Flashcards
Normal Calcium
8.5-10.5 mg/dL
Where is the calcium in the body
> 99% in skeleton
ECF has 0.5%
ECF Calcium
about 46% is bound to albumin
What is the active form of Calcium
Ionized or free Calcium
Most common cause of hypocalcemia
Hypoalbuminemia
Reduced serum calcium + PO4^3-
Elevated phosphorous can cause reduced Ca
Reduced Ca can lead to increase PTH
Increased parathyroid hormone secretion leads to
Increased clast and blast in bone to increase Ca mobilzation
Increased renal Ca reabsorption and decrease PO4 reabsorption
Increased renal activation 1,25 dihydroxy vit D3
Increased clast and blast in bone to increase Ca mobilzation & increased renal Ca reabsorption and decrease PO4 reabsorption leads to
Increased serum Ca which leads to increased calcitonin
Increased renal activation 1,25 dihydroxy vit D3 leads to
Increased intestinal Ca and PO4 absorption which leads to increased serum Ca which leads to increased calcitonin
Hypocalcemia can be seen in
Elderly
Malnourished pts
Pts receiving NaPO4
Causes of hypoCa
Vit D deficiency (renal failure) HypoMg Tissue consumption of Ca Hungry bone syndrome (renal failure) Drug Induced
Vitamin D + Ca
Activation of Vit D leads to increased Ca/P absorption so if there is not enough Vit D there is not enough Ca/P absorption
HypoMg + Ca
Unresponsive to replacement and unresponsive to PTH
TIssue consumption of Ca
Sever pancreatitis secondary to Ca turning into SOAP
Sepsis
Rhabdo
Hungry Bone Syndrome + Ca
Recent thyroidectomy
Bone is avidly incorporating Ca/P into bone
Drug induced hypoCa
Furosemide, calcitonin, bisphosphonates
Chelating agents (citrate and EDTA)
Ethylene glycol
Symptoms of hypoCa
Increased pH (more Ca bind to albumin)
Muscle cramps, tetany
Depression, anxiety, confusion
Prolong QT interval
Chvostek’s sign + HypoCa
Tap on their cheek and their mouth comes up
Trousseau’s Sign + HypoCa
Put a blood pressure cuff on pt and their hand will retract towards arm
HyperCa + EKG
Shortened ST interval
Arrhythmias
HypoCa + EKG =
Prolong ST interval
Acute Symptomatic Hypocalcemia Treatment
100-300 mg of Ca IV over 5-10 minutes (gluconate)
- Last for 1-2 hours so continuous infusion of 0.5-2 mg/kg/hr
Rate of Ca infusion
No more than 60 mg per minute bc of cardiac dysfunction
Ca + Precipitation
Don’t add bicarbonate or phosphate
Chronic Asymptomatic HypoCa Treatment
If hypoMg, give Mg No bisphosphonates bc of hungry bone Oral Ca and Vit D - Ca: 1 to 3 g/day up to 2 to 8 g/day - D: 50,000 u/d but if renal use 1,25 OH D3 0.5-3 mcg/d
Calcium chloride =
27% elemental Ca
- Often leads to hyper symptoms due to high potentcy
Calcium gluconate =
9% elemental Ca
Normal Phosphate
2.5-4.5 mg/dL
Phosphorus is needed for
Cell membranes, nucleic acids, mitochondrial function Enzymatic reaction regulation Oxygen and hemoglobin dissociation High energy bonds of ATP Bone formation
***Phosphorus is mainly
intracellular
SERUM LEVELS DO NO ACCURATELY REFLECT TOTAL BODY STORES
Normal Levels for Children less than 12
4-5.6 mg/dL
Phosphorous homeostasis
Western Diet provides 800-1600 mg and 60-80% is absorbed
- Low Vit D and low P increase absorption
- Reabsorption is inhibited by PTH and increased Vit D3
Mild to moderate hypoP
1-2 mg/dL
Sever hypoP
less than 1 (symptoms)
Causes
Decreased GI absorption
Reduced tubular reabsorption
Internal redistribution
Decreased GI absorption causing hypoP
P binding drugs: aluminum agents, sevelamer Decreaseintake Glucocorticoids Vit D def Hypoparathyroidism Diarrhea Steatorrhea (fat in the poop)
Reduced tubular reabsorption causing hypoP
Hyperparathyroidism
Burn recovery
Faconi syndrome
Internal redistribution causing hypoP
Refeeding syndrome IV nutrition Parathyroidectomy (hungry bone) Insulin Glucagon Calcitonin
Define refeeding syndrome
Mitochondria are so starved for energy bc no enough P that when it enters it goes ECF to ICF and paralyzes the body
Major conditions associated with severe hypoP
Alcoholism, IV TPN
Antacids
Treatment of severe DKA
Symptoms of hypoP
Encephalopathy Impaired myocardial contracility (CHF) Myopathy, dysphagia Hemolysis, defective clotting Prolonged rickets and osteomalacia
Treatment of HypoP
12-14 mmol/L to TPN
Infusion fof 15 mmol/250 mL of D5W or NS over 3 hours
Doses of 15-30 mmol can be given over 1-3 hrs if pts has normal Ca
Monitoring with treatment of HypoP
Q6H
Mild-moderate or asymptomatic hypoP Treatment
Oral P salts 1.5-2 g daily in divided doses and should correct in 7-10 days
- Renal insufficiency reduced to 1 g
