CLINICAL CHEMISTRY
1
WATER BALANCE & ELECTROLYTES
Part Two
ELECTROLYTES

Electrolytes

2
ELECTROLYTES
 General

dietary requirements
Most need to be consumed only in small
amounts as utilized
3
ELECTROLYTE FUNCTIONS
4
ELECTROLYTE PANEL

Panel consists of:
5
ANALYTES OF THE ELECTROLYTE
PANEL
 Sodium
(Na)–
6
FUNCTION: SODIUM

Influence on regulation of body water

Neuromuscular excitability

Na-K ATP-ase Pump
7
REGULATION OF SODIUM


Concentration depends on:
Renal regulation of sodium
 Kidneys can conserve or excrete Na+ depending on ECF
and blood volume
8
REFERENCE RANGES:
SODIUM

Serum


Urine (24 hour collection)
9
SODIUM
 Urine
testing & calculation:
10
DISORDERS OF SODIUM HOMEOSTASIS


Hyponatremia: < 136 mmol/L
 Causes of:
Hypernatremia:> 150 mmol/L
 Causes of:
11
HYPONATREMIA
1.
Increased Na+ loss
12
HYPONATREMIA
2.
Increased water retention
13
HYPONATREMIA
3.
Water imbalance
14
SODIUM
Note:

15
CLINICAL SYMPTOMS OF HYPONATREMIA
 Depends
on the serum level
16
HYPERNATREMIA
1.
Excess water loss
17
HYPERNATREMIA
2.
Increased intake/retention
3.
Decreased water intake
18
CLINICAL SYMPTOMS OF HYPERNATREMIA

Involve the CNS
19
SPECIMEN COLLECTION: SODIUM

20
ANALYTES OF THE ELECTROLYTE PANEL

Potassium (K+)
 the major cation of intracellular fluid

Diet
 easily consumed by food products such as
bananas
21
FUNCTION: POTASSIUM
 Critically
important to the functions of
neuromuscular cells
22
REGULATION OF POTASSIUM

Kidneys
Diet
 Cell Uptake/Exchange

23
REFERENCE RANGES:
POTASSIUM

Serum (adults)

Newborns

Urine (24 hour collection)

24
DISORDERS OF POTASSIUM
HOMEOSTASIS

Hypokalemia

Hyperkalemia
25
HYPOKALEMIA
1.
Non-renal loss
26
HYPOKALEMIA
2.
Renal Loss
3.
Cellular Shift
4.
Decreased intake
27
MECHANISM OF HYPOKALEMIA
RBC
K+ moves into RBCs to preserve electrical balance,
causing plasma potassium to decrease.
28
( Sodium also shows a slight decrease )
CLINICAL SYMPTOMS OF HYPOKALEMIA
29
HYPERKALEMIA
1.
Decreased renal excretion
2.
Cellular Shift
30
HYPERKALEMIA
3.
Increased intake
4.
Artifactual
31
CLINICAL SYMPTOMS OF HYPERKALEMIA
32
SPECIMEN COLLECTION: POTASSIUM
33
ANALYTES OF THE ELECTROLYTE PANEL
 Chloride
(Cl-)

34
FUNCTION: CHLORIDE
35
REGULATION OF CHLORIDE

Regulation via diet and kidneys
36
REFERENCE RANGES: CHLORIDE

Serum


24 hour urine


CSF
37
DETERMINATION: CHLORIDE

Specimen type
DISORDERS OF CHLORIDE HOMEOSTASIS

Hypochloremia

Hyperchloremia
39
HYPOCHLOREMIA

Decreased serum Cl
40
HYPERCHLOREMIA

Increased serum Cl
41
ANALYTES OF THE ELECTROLYTE PANEL

Carbon dioxide/bicarbonate (HCO3-)


Total plasma CO2= HCO3- + H2CO3- + CO2
42
FUNCTION:
BICARBONATE ION

___________________________________________
 continuously produced as a result of cell
metabolism,
 the ability of the bicarbonate ion to accept a
hydrogen ion makes it an efficient and effective
means of buffering body pH
 dominant buffering system of plasma
43
REGULATION OF
BICARBONATE ION
 Acidosis:
 Alkalosis:
44
REGULATION OF BICARBONATE
ION

Kidney regulation requires the enzyme carbonic
anhydrase - which is present in renal tubular cells &
RBCs
Reaction:
45
REFERENCE RANGE:
BICARBONATE ION

Total Carbon dioxide (venous)


Bicarbonate ion (HCO3–)

46
SPECIMEN COLLECTION: BICARBONATE
ION
47
ELECTROLYTE BALANCE

Anion gap –
48
ELECTROLYTE SUMMARY

cations (+)
Na 142
 K
5
 Ca
5
 Mg
2
154 mEq/L


anions (-)
Cl
105
 HCO324
 HPO422
 SO4-2
1
 organic acids
6
 proteins
16

154 mEq/L
49
ANION GAP

Anion Gap Calculations
50
FUNCTIONS OF THE ANION GAP

Causes in normal patients

Increased AG –

Decreased AG 51
REFERENCES




Bishop, M., Fody, E., & Schoeff, l. (2010). Clinical
Chemistry: Techniques, principles, Correlations. Baltimore:
Wolters Kluwer Lippincott Williams & Wilkins.
http://thejunction.net/2009/04/11/the-how-to-authority-fordonating-blood-plasma/
http://www.nlm.nih.gov/medlineplus/ency/article/002350.ht
m
Sunheimer, R., & Graves, L. (2010). Clinical Laboratory
Chemistry. Upper Saddle River: Pearson .
52