This document discusses potassium and its clinical importance. It covers the following key points: - Potassium is a major intracellular cation, maintaining a concentration gradient between intracellular and extracellular fluid with the help of the sodium-potassium pump. - Hyperkalemia can result from kidney failure, tissue damage, violent muscle contraction, Addison's disease, or diabetes mellitus. Hypokalemia is usually due to depletion of total body potassium through GI loss, urinary loss, or intracellular shifting. - Various conditions that can cause hyperkalemia or hypokalemia are described in detail, focusing on the underlying mechanisms of potassium imbalance. Close monitoring of potassium levels is important for managing certain diseases.

1. Clinical Biochemistry
SIMS-305
Dr. Ali Raza
Senior Lecturer
Centre for Human Genetics and Molecular Medicine (CHGMM),
Sindh Institute of Medical Sciences (SIMS), SIUT.
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2. POTASSIUM
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3. • major intracellular cation
• Intracellular [K+] = 150 mEq/L
• Plasma potassium is 3.5-5 mEq/L.
• Na+-K+ ATPase or sodium pump maintains
concentration gradient.
• Filtered by the glomeruli of the kidney and
reabsorbed by proximal tubules
POTASSIUM
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4. POTASSIUM FUNCTIONS
Many functions of potassium and sodium are carried
out in coordination with each other
• Influences the muscular activity
• Involved in acid-base balance
• Involved in neuromuscular irritability and nerve
conduction process.
• It has an important role in cardiac function
• K+ as cofactor: Pyruvate kinase
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5. Potassium -- CLINICAL IMPORTANCE
• High and low values are clinically important.
• Extracellular levels of potassium are
measured on a sample of serum.
• RBCs contain a large amount of potassium,
care must be taken that sample is not hemolysed.
• On standing, potassium value changes,
Plasma potassium must be measured as
soon as possible on fresh sample.
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6. Potassium-- CLINICAL IMPORTANCE
• Hyperkalaemia
• Hypokalaemia
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7. Potassium-- CLINICAL IMPORTANCE
Hyperkalaemia
Excretion of potassium in normal persons are so
effective that it is difficult to produce hyperkalaemia
by simply increasing the oral intake.
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8. Hyperkalaemia are due either to:
1. Anuria
2. Tissue damage
3. Violent muscle contraction
4. Addison’s disease
5. Diabetes mellitus
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9. Hyperkalaemia
1- Kidney failure :
 Anuria (failure of the kidneys to produce urine):
Complete shut-down of kidney function
• Decreased excretion of potassium cause results in
increasing conc. of K+.
• kidney failure is associated with sudden release of
intracellular potassium from any organ.
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10. Hyperkalaemia
2-Tissue damage:
Damage to body cells from any cause in release of
cell contents including K+ into ECF.
 Examples
Crush injuries, with damages to large volumes of
Muscle tissue,
Massive hemolysis
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11. Hyperkalaemia
3-Violent Muscle Contraction:
Vigorous Exercise :
• Produces a release of K+ from muscle cells into the
extracellular space and may increase in plasma K+.
• Same mechanism is responsible for the increase seen
in status epilepticus.
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12. Hyperkalaemia
4-Addison’s Disease:
• In the absence of aldosterone,
the exchange of sodium for potassium in
the kidney is reduced,
• with increased loss of sodium and retention of K+ in
body.
Low serum sodium and high serum K+
are characteristic of this disease.
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13. Hyperkalaemia
5-Diabetes Mellitus:
• In ketoacidosis, substantial loss of intracellular K+ to
the ECF.
• Due to increased activity of Na+-K+ ATPase which
results from impaired glucose metabolism.
• If ketoacidosis presents for a long time, there will
be major depletion of total body K+.
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14. Hyperkalaemia
 Diabetes Mellitus:
• Treatment with insulin allows
a) resumption of Na+ pump activity
b) movement of K+ back into the cells
c) an abrupt fall in plasma K+
• Administration of K+ to restore lost in the urine during
the period of acidosis.
Frequent monitoring of K+ is vital to DM
with ketoacidosis.
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15. Low serum K+ usually results from the
depletion of total body K+.
Potassium level < 3.5 mmol/L.
Hypokalaemia
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16. K+, dietary deficiency is uncommon
• All food contains large quantities of K+.
• Dietary supplements of K+ are required only in patients
a) with some disease
b) Drugs use which causes potassium depletion.
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17.  Common causes of hypokalaemia are:
1. Loss of K+ in GI secretions
2. Loss of K+ in urine
3. Loss of extracellular K+ into the intracellular space
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18. Hypokalaemia
1- Loss of K+ in GI secretions
• Prolonged vomiting
• Severe diarrhoea
• Operation (ileostomy)
• Laxative: Develop chronic mild diarrhoea cause low K+
• Mucous secreting tumour called a Cillous adenoma.
– Secretes large amounts of K+ into lumen of colon.
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19. Hypokalaemia
2-Loss of K+ in urine
• Many medications decrease total body sodium such
as some diuretics also cause loss of K+.
• Thiazides, Acetazolamide for HTN and heart
• Thiazide, diuretics drug causes of low plasma K+.
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20. Hypokalaemia
3-Loss of extracellular K+ into the intracellular space:
• Treatment of diabetes ketoacidosis causes a rapid fall in
plasma K+ from a state of hyperkalaemia to normal and
then to hypokalaemia as the acidosis is brought under
control.
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21. Elements Requirement Group
1
Zn, Fe, and Mn
2
Na, K, Ca,
3
As, CN–, Hg
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Sodium Pump is also called
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Sodium Pump is found in plasma membrane of
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How many sodium and potassium ions are
pump outside and inside the cell membrane
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write functions of Sodium – (3)
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Specific conditions in which hypernatraemia
occurs (3)
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Specific conditions in which Hyponatraemia
occurs (3)
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22. Elements Requirement Group
1 Zn, Fe, and Mn < 100 mg III/ Trace elements, Essential elements
2 Na, K, Ca, >100 mg II/macro elements, Principal elements
3 As, CN–, Hg Group V
4 Sodium Pump is also called Na+-K+ ATPase
5 Sodium Pumps are found in plasma membrane of Intestinal and Renal cells
6 How many sodium and potassium ions are pump
outside and inside the cell membrane
______ Na+ (outside)
______ K+ (Inside)
7 write functions of Sodium – (3) Fluid balance , Blood viscosity
Acid-base balance
Neuromuscular excitability
8 Specific conditions in which hypernatraemia occurs
(3)
Simple Dehydration
Diabetes Insipidus
Osmotic Loading
Excess Sodium
9 Specific conditions in which Hyponatraemia Diuretic medication
Excessive sweating
Kidney diseases
Congestive heart failure
Gastrointestinal loss
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