SODIUM
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3rd Year / 1st Semester
It is the major cation of ECF and forms 90% of all ECF cations.
It is the main cation which determines the Osmolality of ECF.
Osmolality = 2 Na + Glucose (mg / dl) + BUN (mg / dl)
20 3
Its main function is
• Regulation of acid-base balance
• Maintains osmotic pressure and water balance
Main Source
• Common salt (NaCl) used in cooking.
• Foods - Cheese, wheat germ, bread carrots, eggs, milk, nuts, radish.
About 4 gm of sodium (about 10 gms of NaCl) are ingested everyday.
About 95% of Na is excreted in the urine everyday.
Metabolism
• The metabolism of Na is influenced by Adrenocorticoid hormones
(Glucocorticoid and Mineralocorticoids) and ADH (anti-diuretic hormone).
The corticosteroids increase the absorption of Na and Cl in the kidney
and decrease their excretion by the sweat gland, salivary gland and
gastrointestinal tract.
They cause increased excretion of potassium by the kidney (Na-K-ATPase ion pump moves 3 Na outside and 2 K inside cell)
• The ADH controls the movement of water in the kidney.
Hyponatremia
It is a condition of decreased sodium in ECF.
Causes of Hyponatremia
• Decreased intake of salt(NaCl)
• Burns
• Massive sweating
• Prolonged vomiting and diarrhea
• Addison’s disease(deficiency of Mineralocorticoids)
Symptoms
The ECF becomes Hypotonic causing more loss of water from ECF due to osmosis.
• Decreased blood pressure
• Vasoconstrictive shock
• Nausea, vomiting, cramps
• Circulatory failure causing death.
Treatment
• IV saline
Hypernatremia
It is condition of increased sodium in the ECF.
Causes of Hypernatremia
• Excessive intake of salt(NaCl)
• Cushing’s syndrome(excessive Mineralocorticoids)
• Head injury
Symptoms
The ECF become hypertonic causing excessive entry of water in the ECF due to osmosis.
• Increased blood pressure
• Peripheral edema
• Pulmonary edema
• Respiratory failure causing death
Treatment
• Diuretics causing loss of water from ECF in urine.
Estimation of Sodium
Specimen : Serum, Plasma, CSF and Urine
Methods : Chemical Methods
Flame Photometer
Atomic Absorption Spectrophotometer (AAS)
Ion Selective Electrode (ISE) (method of choice)
Reference range:
Specimen Reference range
Plasma, Serum 135 – 145 mmol / L
Urine 40 – 220 mmol / L
CSF 135 – 150 mmol / L
POTASSIUM
It is the major cation of Intracellular fluid (ICF).
Its main function inside the cell is
• regulation of acid-base balance
• osmotic pressure and water balance.
Main Source
• Foods – Chicken, dried apricots, dried peaches, bananas, oranges, pineapples, potatoes.
About 4 gm of potassium (mainly in foods) are ingested everyday.
Metabolism
• The metabolism of potassium is mainly controlled by the Mineralocorticoids.
The kidney is the main organ of potassium regulation and excretion in urine.
Hypokalemia
It is condition of decreased potassium in the serum.
Causes of Hypokalemia
• GIT-Severe vomiting and diarrhea, Large doses of laxatives.
• Kidney – Diuretics (Thiazides)
• Insulin overdose
• Metabolic alkalosis
• Cushing’s syndrome (excessive Mineralocorticoids)
• Cancer therapy- chemotherapy, radiotherapy
Symptoms
• Weakness, fatigue and constipation
• Muscle weakness or muscle paralysis causing difficulty in breathing
• In heart it cause arrhythmia leading to sudden death.
Treatment
• Oral KCl or IV replacement.
Hyperkalemia
It is a condition of increased potassium in the serum.
Causes of Hyperkalemia
• Acute or chronic renal failure
• Hemolysis
• Prolonged tourniquet
• Diuretics (other than thiazides)
• Acidosis
• Addison’s Disease (deficiency of Mineralocorticoids)
Symptoms
• Muscular weakness, tingling, numbness
• Mental confusion
• Arrhythmias causing cardiac arrest and death
Treatment
Treatment should be immediately started if serum potassium level is above 6 mmol / L
• IV calcium
• Glucose, Bicarbonate or insulin promotes movement of potassium inside the cell
• Diuretics (thiazides)
• Enema
Estimation of Potassium
Specimen : Serum, Plasma, sometimes whole blood and Urine
Hemolysis must be avoided
Methods : Chemical Methods
Flame Photometer
Atomic Absorption Spectrophotometer (AAS)
Ion Selective Electrode (ISE) (method of choice)
Reference range:
Specimen Reference range
Plasma, Serum 3.5 – 5.0 mmol / L
Urine 25 – 125 mmol / L
CALCIUM
It is present in large amounts in the body,
Distribution of calcium
Bones & Teeth
99% Blood & ECF
1%
Free Ionized calcium
45 % Bound calcium
40 % Complexed calcium
15 %
Calcium is deposited in bones and teeth as calcium phosphate.
The ionized calcium plays very important role in the body
• Participates in blood coagulation
• Maintains excitability of heart and muscle
• Maintains excitability of nerves
Main Source
• Foods –Milk and Cheese are the richest source of calcium
Egg yolk, beans, lentils, nuts, cabbage
Metabolism
The calcium and phosphorus metabolism is controlled by hormones
1. Parathyroid hormone
It is secreted by parathyroid gland
It mainly acts on the
• BONE causing breakdown and release of calcium and phosphorus
• KIDNEY it promotes excretion of phosphorus and absorption of calcium.
2. Vitamin D
It mainly acts on the
• INTESTINE promoting absorption of calcium and phosphorus
• BONE causing formation of bone and utilization of calcium.
3. Calcitonin
It decreases bone breakdown, antagonist of PTH
4. Others-
• Thyroxin- promotes bone breakdown
• Estrogen and androgens- promote bone formation
HYPOCALCEMIA
It is defined as a condition of decreased level of serum calcium.
The most common symptoms of hypocalcemia are parasthesia, muscle cramps, tetany and seizures.
E.g. Acute pancreatitis
Renal disease
Rhabdomyolysis
HYPERCLCEMIA
It is defined as a condition of increased level of serum calcium.
The symptoms of hypercalcemia do not cause acute problems and may not be life threatening.
E.g. Malignancy
Multiple myeloma
Hyperparathyroidism
Prolonged immobilization
Estimation of Calcium
Specimen:
• The preferred specimen for TOTAL SERUM CALCIUM determination
- Serum
- Heparin (sodium, lithium) plasma
Precautions: It should be collected without venous stasis.
Anticoagulants such as OXALATE or EDTA bind calcium tightly and interfere in calcium estimation, therefore should be avoided.
• The preferred specimen for IONIZED SERUM CALCIUM determination
- Heparinized whole blood
Precautions: Dry heparin products with small amounts of Ca or Zn eliminate the interference by heparin.
• Urine calcium dtermination:
Accurately timed urine collection is preferred
The urine should be acidified with 6 mol/L HCl, with approximately 1 ml of acid added for each 100 ml urine.
Method
• The two commonly used methods for total calcium analysis are
o OCPC (ortho-cresolphthalein complexone) method
o Arsenazo-III dye method.
• For ionized calcium
o ISE (Ion selective electrode) method
Reference range
Total calcium
Child 8.8 – 10.8 mg/dl
Adult 8.0 – 10.0 mg/dl
Ionized calcium
Child 4.8 – 5.5 mg/dl
Adult 4.6 – 5.3 mg/dl
CHLORIDE
It is the major anion of ECF
Chloride disorders are often result of the same causes that disturb sodium levels because Cl passively follows sodium.
Its main function along with sodium is
• Water balance
• Acid-base balance
• Osmotic pressure regulation
• In gastric juice, chloride plays important role in production of HCl.
Requirement and Metabolism
The intake of chloride is satisfactory as long as sodium intake is
adequate since chloride occurs almost entirely as sodium chloride.
Abnormalities of sodium metabolism are generally accompanied by
abnormalities in chloride metabolism.
Hypochloremia, chloride deficit, is hence observed in conditions such as Diarrhea, profuse sweating, prolonged vomiting etc.
Distribution of Chloride
Plasma or serum 300 - 365 mg/dl
CSF 350 - 440 mg/dl
MAGNESIUM
It is the fourth most abundant cation in the body.
Distribution of Magnesium
Bone 53%
Muscle 46%
Serum < 1% ( 1/3rd bound to protein and 2/3rd exists in free or ionized state)
Function of Magnesium
Magnesium plays important role in the cardiovascular, metabolic and neuromuscular functions.
It is essential cofactor in more than 300 enzymes
• Glycolysis
• Neuromuscular transmission
• Synthesis of carbohydrates, proteins, lipids and nucleic acids
• Release and function of some hormones
Metabolism of magnesium
The overall regulation of body magnesium is controlled by the kidney and is related to the metabolism of sodium and potassium.
PTH increases the renal reabsorption and absorption of magnesium in the intestines.
Aldosterone has opposite effect of PTH on the magnesium causing renal excretion.
TRACE ELEMENTS
Trace elements are usually metals and are usually associated with enzymes or proteins,
They are needed in the body in minute (trace) amounts.
Deficiencies typically impair one or more biochemical functions and excesses concentrations are associated with some toxicity.
Essential Trace elements- Iron, Copper, Zinc
Essential Ultra Trace elements- Manganese, Cobalt, Selenium, etc
Non-essential Trace elements- Fluoride, Gold, etc.
IRON
Distribution
Iron forms important integral component of Hemoglobin(90% of all iron in
the body) in the blood, Myoglobin in the muscle and several
enzymes-Cytochrome, peroxidases, catalases and many enzymes of Kreb’s
cycle.
Iron is stored as FERRITIN and HEMOSIDERIN, primarily in the bone marrow, spleen and liver.
Iron is transported in the plasma bound to TRANSFERRIN and Albumin.
Function of Iron
Transport of O2 and CO2 by the hemoglobin.
Iron must remain in Fe2+ state in order to transport oxygen( oxidized Fe3+ forms methemoglobin)
Cytochromes participate in ETC and ultimately result in production of energy as ATP.
Iron plays important role as Anti-oxidant (Peroxidases and catalases convert harmful oxidant H2O2 to water)
Dietary requirement
The chief source of iron are all green vegetables, spinach, Liver, dates, all fruits that turn dark after cutting, egg yolk.
In an adult male, the average loss of 1mg of iron per day must be replaced by dietary sources.
Pregnant or pre-menopausal women and children have greater iron requirements, often obtained by dietary supplementation.
Metabolism of Iron
Absorption of iron is primarily controlled from the intestines.
The dietary iron is mainly in the form of Fe3+ and must be converted to
Fe2+ by vitamin C before it can be absorbed. In the plasma, Transferrin
transports and releases Fe in the bone marrow where it gets incorporated
in the hemoglobin. After 120 days the RBC breaks in the spleen, liver
and macrophages. The iron is returned to the IRON POOL.
Iron excretion
Iron is lost each day from the body in small amounts mainly in the urine and feces in the form of epithelial cells and RBC.
Women lose considerable amount of iron during menstruation.
Clinical Disorders
Iron Deficiency Anemia
It is a condition of Anemia due to decreased serum iron.
It is the one of the most prevalent disorders known, with 15% of the world wide population affected.
Pregnant women, Lactating women, young children and adolescent, women of
reproductive age are at higher risk of developing Iron deficiency
anemia.
Parameters of Iron deficiency anemia
• Decreased serum iron
• Increase in Transferrin
• Increased TIBC (total iron binding capacity)
• Decreased serum Ferritin ( better marker)
Iron Overload (HEMOCHROMATOSIS)
Iron overload is usually caused due to excessive absorption of iron from
the diet and condition is referred to as Hemochromatosis.
Parameters of Iron overload
• Increased serum iron
• Decreased Transferrin
• Decreased TIBC
• Increased serum Ferritin
COPPER
Copper is mainly found associated to enzymes and are called as Metalloenzymes e.g., cerruloplasmin, cytochrome c etc.
Copper is essential for
• Healthy skin and hair
• Normal pigmentation
• Absorption of iron in the intestines
• Protection from Free radicals(anti-oxidants)
Metabolism of copper
Copper is mainly found in foods rich in Iron- Shell fish,Liver, legumes, nut, egg yolk etc.
It is absorbed from the intestines and both Iron and Zinc compete with copper for absorption.
Copper is transported in plasma bound to Cerruloplasmin
Disorders of copper metabolism
Copper deficiency is rare. The deficiency is usually associated with decreased pigmentation, mental deterioration.
Copper excess is associated with Wilson’s disease, where there is copper
accumulation in liver, brain, kidney, cornea etc, resulting in liver
cirrhosis and brain lesion.
ZINC
Zinc is also mainly found associated with enzymes and is essential for
• Growth, wound healing
• Healthy skin and hair
• Normal reproductive function
• Normal function of Immune system
• Protection from Free radicals
Metabolism of Zinc
The main dietary sources of zinc are milk and dairy products, meat, fish, whole grains and seeds
It is actively absorbed from the intestines and transported in the plasma bound to albumin.
Zinc is highly concentrated in the hair, skin, nails and testes.
Disorders of Zinc metabolism
Deficiency of zinc result from dietary insufficiency and results in
growth retardation, skin lesions, slow wound healing, impotence and
susceptible to infection .
Zinc excess is rare.
MANGANESE
Manganese is associated with many enzymes.
It helps in nourishment of nerves and brain, in coordination of nerve impulses and muscular actions.
Manganese is found in citrus fruits, green vegetables, fish and raw egg yolk.
A deficiency of manganese results in poor elasticity in muscles, confused thinking and poor memory.
Manganese toxicity is rare.
FLUORIDE
Fluoride helps in preventing dental caries.
It prevents bone loss and stimulates bone formation and lessens the occurrence of bone fracture.
Fluoride is found in goat milk, garlic, cabbage, spinach etc.
Fluoride is absorbed from the intestines and almost totally distributed to the bones and teeth.
