Electrolytes: Part 2 (Calcium & Phosphate) Flashcards
Most abundant cation in the body
Calcium
Calcium is present almost exclusively in ______ (____________________________)
plasma
(Extracellular Fluid Ca2+)
Distribution
___ - Bones
___ - Blood (plasma) and other ECF
99%
1%
Blood Ca2+ (intravascular) is
______________ higher than other ECF
(interstitial)
5,000-10,000
Absorption:__________ (________)
duodenum
acidic pH
Enumerate the functions of Calcium
- Blood coagulation (especially ionized Ca2+ ),
enzyme activity - Skeletal and Cardiac muscle excitability
- Maintenance of Blood pressure
Forms of Calcium
- Ionized Calcium/Free Calcium
- Protein-bound Calcium
- Complexed with anions
How many percent is Ionized Calcium/Free Calcium?
50%
How many percent is Protein-bound Calcium
40%
How many percent is Complexed with anions?
10%
Sensitive and specific marker for calcium
disorders
Ionized Calcium/Free Calcium
Ionized Calcium/Free Calcium is not effected by ________ level
Albumin
T/F: Ionized Calcium/Free Calcium is pH independent
FALSE; pH dependent
________ pH: Ca2+ will be displaced from
albumin ((high/low)) free Ca2+)
Acidic
high
_________ pH: Ca2+ binds with albumin ((high/low))
free Ca2+)
Alkaline
low
Most active form and most abundant
Ionized Calcium/Free Calcium
Freely circulating calcium:
Ionized Calcium/Free Calcium
T/F: Ionized Calcium/Free Calcium is NOT bound to any substances
T
T/F: Ionized Calcium/Free Calcium circulates as calcium itself
T
Bound to _________; therefore, affected by __________
levels
Protein-bound Calcium
albumin
↓Albumin = (low/high) Protein + Ca2+ affecting total Ca2+
low
2nd most abundant
Protein-bound Calcium (40%)
Example of Complexed with anions
● HCO3-, citrate, lactate
Among the forms of calcium, only the __________ and _________________ are measured
Total Calcium
Ionized Calcium
Total Ca2+ = ___________ + Protein-bound +
Complexed with Anions
Ionized
only measures itself
Ionized Ca2+
REGULATION of Calcium
- Hypercalcemic
- Hypocalcemic
subs. that can ↑ Ca2+ levels
Hypercalcemic
enumerate the hypercalcemic substances
A. 1,25-Dihydroxycholecalciferol [1,25-(OH)2-D3]
B. Parathyroid Hormone (PTH)
1,25-Dihydroxycholecalciferol increases the _____________________, _________________ of Ca2+
intestinal absorption
renal reabsorption
Increased mobilization of Ca2+ from bones by
promoting bone __________ process.
1,25-Dihydroxycholecalciferol [1,25-(OH)2-D3]
resorption
Secreted by parathyroid gland
Parathyroid Hormone
Conserved Ca2+ by increasing ____________
Parathyroid Hormone
renal reabsorption
Increases level by mobilizing bone Ca2+
Parathyroid Hormone
How does Parathyroid Hormone increases level by mobilizing bone Ca2+
By activating bone resorption process
PTH activates ___________ (bone
macrophage) which destroys bone
tissues in which ____ of Ca2+ are found.
Therefore, it will liberate Ca2+ = (inc/dec) Ca2+
osteoclasts
99%
icn
Suppresses urinary loss of Ca2+
Parathyroid Hormone
Stimulates activation of inactive Vit. D
(______________) to active Vit. D3 (________)
Parathyroid Hormone
cholecalciferol
kidneys
Activation through the process of
______________ (addition of OH- in the liver on
the ____________ position) =_____________________
○ still inactive
hydroxylation
25th
25-hydroxycholecalciferol
Next hydroxylation happens in the ___________ on
the ______________ =
1,25-Dihydroxycholecalciferol (______________)
kidney
1st position
activated Vit. D3
subs. that can ↓ Ca2+ levels
Hypocalcemic
Enumerate hypocalcemic substance
A. Calcitonin
Secreted by the ____________________ of thyroid
glands
Calcitonin
parafollicular C cells
Inhibitor of ____ and ______
PTH
Vit. D3
Inhibits bone resorption
Calcitonin
bone destruction by osteoclast
bone resorption
Promotes urinary excretion of Ca2+
Calcitonin
Symptoms are usually neuromuscular excitability
(represent as tetany)
HYPOCALCEMIA
tetany is represented by:
muscle spasms,
paresthesia
What is pamamanhid
Paresthesia
HYPOCALCEMIA Only occurs: If Total Ca2+ _____ mmol/L (____mg/dL)
<1.88
<7.5
HYPOCALCEMIA 2 signs
Chvostek’s Sign
Trousseau’s Sign
contraction of facial
muscles in response to tap
Chvostek’s Sign
uses BP cuff
Trousseau’s Sign
BP cuff (inflated at _________ above the patient’s ____________ for 3-5 minutes)
20 mmHg
systolic
Trousseau’s sign
Shows ______/___________ spasm
carpal/Carpopedal
Causes of Hypocalcemia
● Hypoparathyroidism
● Vitamin D deficiency
● Malabsorption
● Alkalosis
● Acute pancreatitis
● Hypomagnesemia
● Hypermagnesemia
● Hypoalbuminemia
hypercalcemic
Hypoparathyroidism
hypercalcemia
Vitamin D deficiency
alkaline in the blood; the calcium will
(bind/lyse) to albumin
Alkalosis
bind
In Alkalosis
(low/high) Ionized Ca2+
(low/high)Total Ca2+
low
high
_____ (secreted by pancreas) will enhance
intestinal binding of Ca2+
Acute pancreatitis
Lipase
↓Mg2+
Hypomagnesemia
Inhibits parathyroid hormone (PTH) secretion
Hypomagnesemia
Impairment of parathyroid hormone action
Hypomagnesemia
Vitamin __ resistance
Hypomagnesemia
D
↑Mg2+
Hypermagnesemia
Inhibits parathyroid hormone secretion
Hypermagnesemia
↓Albumin
Hypoalbuminemia
T/F: Hypoalbuminemia/ Ionized calcium is not affected. Only affects total calcium.
T
For every ↓1 g/dL ALB = ↓___mmol/L TC or
___ mg/dL TC
0.2
0.8
Causes of Hypercalcemia
● Hyperparathyroidism
● Hyperthyroidism
● Benign Familial Hypocalciuria
● Malignancy
● Acidosis
● Increased Vitamin D
● Thiazide diuretics
● Prolonged immobilization
main cause of hypercalcemia
Hyperparathyroidism
PTH excess
Hyperparathyroidism
mainly affect ionized Ca+ levels
Hyperparathyroidism
can also affect parathyroid glands because
of ______________
Hyperthyroidism
proximity
___________ does not have Ca+ (remains in the
blood)
Benign Familial Hypocalciuria
Urine
↑Ca+ (separates/adhere) with albumin
Acidosis
separates
↑ionized Ca+ , (inc/dec) total Ca+
Acidosis
↓
↑bone resorption
Prolonged immobilization
Specimun used in the laboratory analysis of Calcium
Serum
Heparinzed plasma
Timed urine sample
What type of heparinized plasma is acceptable in Calcium laboratory analysis
Lithium heparin
Never use EDTA or oxalates as they
__________ causing false decrease
chelate Ca2+
Timed-urine sample must be __________
must be acidified
How to acidify urine sample:
Addition of ________ of ___________ per
________ of urine
1mL
6 mol/L HCl
100 mL
Considerations/Variables for Ionized Ca2+:
- Sample must be collected anaerobically
(must not be exposed to air) - Use dry heparin anticoagulant (if plasma)
air exposure of blood causes the
release of _____
CO2
_______ blood = Ca2+ binds with
___________ = false (inc/dec) in ionized calcium
alkaline
albumin
↓
Alternative in Laboratory Analysis of Calcium Considerations
Serum tubes collected using
ETS
Clotted and centrifuge for ___ minutes
at RT
10
Laboratory methods for Calcium
A. Precipitation and Redox Titration
B. Ortho-Cresolpthalein Complexone Dyes
C. EDTA Titration Method
D. Ion Selective Electrode
E. Atomic Absorption Spectrophotometry
F. Flame Emission Photometry
2 types of Precipitation and Redox Titration
- Clark Collip Precipitation
- Ferro Ham Chloranilic Acid Precipitation
Clark Collip Precipitation End Product:
Oxalic acid
Clark Collip Precipitation End Product color:
Purple color
Ferro Ham Chloranilic Acid Precipitation end product:
Chloranilic acid
Ferro Ham Chloranilic Acid Precipitation end product end color
Purple color
Colorimetric method
Ortho-Cresolpthalein Complexone Dyes
Interference of Ortho-Cresolpthalein Complexone Dyes
Mg2+
the interference Mg2+ causes false (inc/dec)
Increase
Mg2+ inhibitor/chelators is added
(__________________)
8-hydroxyquinoline
Dye in Ortho-Cresolpthalein Complexone Dyes
Arzeno III
EDTA Titration Method example
Bachara, Dawer and Sobel
Liquid membrane
Ion Selective Electrode
reference method for calcium
Atomic Absorption Spectrophotometry
Almost all phosphorus are combined with O2
forming __________
phosphate
Predominant intracellular anion
Phosphate
● PO4 is inversely related to _______
Ca2+
Phosphate distribution
→ ____ - bones
→ ____- soft tissues
→ ____ - plasma
80%
20%
<1%
Adsorption in phosphates
Jejunum (in diet)
Function of Phosphates
→ Insulin-mediated glucose entry in the cell
→ DNA and RNA structures
→ Energy reservoir
→ Promotes hemoglobin affinity to oxygen
→ Coenzyme
Process present in Insulin-mediated glucose entry in the cell
phosphorylation
Phosphates present in DNA and RNA structures
phosphodiesters
Phosphates present in Energy reservoir
Adenosine triphosphate (ATP)
Phosphate present in Promotes hemoglobin affinity to oxygen
2,3-Biphosphoglyceric acid
Phosphates present in Coenzyme
phosphoric/pyrophosphoric acid
Total phosphate in blood:
12 mg/dL
Phosphates may exist as
Organic Phosphate
Inorganic Phosphate
Organic phosphate how much
8-9 mg/dL
Inorganic phosphate how much
3-4 mg/dL
principal intracellular anion
Organic Phosphate
part of blood buffer
Inorganic phosphate
can maintain blood pH
Inorganic phosphate
the ONLY type measured in the
laboratory
Inorganic phosphate
Forms of Phosphorus
→ Free/Unbound
→ Complexed with ions
→ Protein-bound
Percent of free/unbound phosphorus
55%
Percent of phosphorus complexed with ions
35%
Percent of protein-bound phosphorus
10%
Regulation of phosphate:
A. Parathyroid hormone
B. Vitamin D
C. Growth hormone
(↓PO4-)
Parathyroid hormone
(↑PO4-)
Vitamin D
Growth hormone
Decreases phosphate by renal excretion
Parathyroid hormone
Increases _______________ and ______________ absorption of phosphate
Vitamin D
Intestinal and Renal
Increased phosphate renal reabsorption
Growth hormone
Decreased plasma phosphate concentration
HYPOPHOSPHATEMIA
Very critical for a patient
HYPOPHOSPHATEMIA
why is HYPOPHOSPHATEMIA very critical for a patient?
ATP relies on phosphate
(low/high) PO4- may lead to ATP depletion
low
Severe hypophosphatemia
<1.0 mg/dL
Causes of Hyphophosphatemia
- Alcoholism
- Vitamin D Deficiency
- Renal Tubular Acidosis
- Hyperparathyroidism
- Rickets
- Fanconi Syndrome
- Transcellular shift
most common of hypophosphatemia
Alcoholism
Alcoholism
→ most common of hypophosphatemia bec. it
impairs absorption of phosphate in the
_________
intestine
CAUSES
↑PO4-
Vitamin D Deficiency
CAUSES
PTH (inc/dec)PO4- (by inc. renal excretion)
dec
major cause of hypophosphatemia
Transcellular shift
PO4- in the blood that enters the cell = (inc/dec) PO4- in plasma
Transcellular shift
dec
at risk are patients with Acute/Chronic Renal
Failure
HYPERPHOSPHATEMIA
Causes of HYPERPHOSPHATEMIA
- Renal Disease
- Hypoparathyroidism
- Excess Vitamin D
- Acromegaly
- Lymphoblastic Leukemia
Leading cause of Hyperphosphatemia
Renal Disease
increased GH that (inc/dec) PO4-
Acromegaly
inc
_____________ (immature lymphocytes) have
_____ more phosphate compared to
lymphocytes
Lymphoblastic Leukemia
lymphoblasts
4x
Specimen used in the laboratory analysis of Phosphate
Serum
Heparinized plasma
24hr urine
Variables in the laboratory analysis of phosphates
Hemolysis
Circadian Rhythm
Other anticoagulants
Hemolysis in laboratory analysis of phosphates causes false (inc/dec)
Increase
Hemolysis is false increase due to higher phosphate in ____ compared to _______
RBC
plasma
natural changes that occurs in the body within 24 hrs
Circadian Rhythm
_______ - highest phosphate
Late morning
__________ - lowest phosphate
Evening
Other anticoagulants that is a variable in the laboratory analysis of Phosphates that may interfere with the methods
EDTA
Citrate,
Oxalate
Laboratory method for phosphates
- Fiske Subbarow Method (aka Ammonium
Molybdate Method)
Most commonly used method for measuring
inorganic phosphate
Fiske Subbarow Method (aka Ammonium
Molybdate Method)
Principle:
Phosphorus + ammonium molybdate –> __________________________________ (340 nm)
ammonium phosphomolybdate
Principle
ammonium phosphomolybdate + pictol –»» _____________________ (600 nm)
molybdenum blue
colorless end product ; measured at
340 nm
Ammonium phosphomolybdate:
what region is Ammonium phosphomolybdate:
UV region
most accurate method
Ammonium phosphomolybdate
Alternative method: If UV spectro is not
available, ______ can be added
reducing agent
The addition of RA, will facilitate the
formation of __________________
measured at 600 nm (_______ region)
molybdenum blue
visible
Disadvantage:
___________ pH = reduction of molybdenum blue (false (inc/dec)))
Alkaline
decrease