Mineral Disorders - 4th Year Medicine

Learning Outcomes: Students will be able to define normal and abnormal plasma magnesium, sodium, potassium, and calcium levels; identify disorders associated with abnormal mineral levels; and describe laboratory tools for mineral concentration estimation.

Abundance: Magnesium is the fourth most abundant cation (Mg²⁺) in the body.
Total Body Content: Total body content is 21-28 g.
Normal Serum Levels: Normal serum levels are 1.7 - 2.5 mg/dL.
Distribution:
- 53% stored in bone
- 46% in muscles and soft tissues
- 1% extracellularly in blood and RBCs

Muscles and Nerves: Crucial for proper muscle and nerve function.
ATP Complexation: Forms a complex with ATP, acting as a cofactor for various enzymes in metabolism, replication, and transport.
Metabolism Regulation: Essential for sodium, potassium, calcium, vitamin C, and phosphorus metabolism.
Electrolyte Balance: Maintains electrolyte balance.
Anti-Stress: Possesses anti-stress properties.

Definition: Clinically significant deficiency of less than 1.2 mg/dL.
Renal Causes: Hypercalcemia, tubular disorders in the kidney, hyperaldosteronism, and diuretics.
Extrarenal Causes: Malnutrition, malabsorption (chronic diarrhea or laxative abuse), increased cell uptake of magnesium, and increased bone storage after parathyroidectomy.

Rarity: Rare, mostly in patients with renal failure using magnesium-containing drugs.

Distribution: One-third of total body sodium is found in the skeleton, while the majority is found in extracellular fluids.
Acid-Base Balance: Associated with chloride and bicarbonate for regulating acid-base balance.
Fluid Balance: Important for maintaining body fluids and protecting against excessive fluid loss.
Muscle and Cell Function: Crucial for normal muscle irritability and cell permeability.

Sodium Salt Administration: Rapid sodium salt administration.
Adrenal Cortex Hyperactivity: Cushing's disease.
Corticotrophin Administration: Corticotrophin (ACTH) and cortisone administration.
Dehydration: Dehydration, as seen in diabetes insipidus.

Adrenocortical Insufficiency: Adrenocortical insufficiency due to sodium loss.
Chronic Renal Failure: Cases of chronic renal failure.
Liver Cirrhosis: Liver cirrhosis.
Congestive Heart Failure: Congestive heart failure.
Gastrointestinal Fluid Loss: Excessive loss of gastrointestinal fluids (severe diarrhea).
Excessive Sweating: Excessive sweating.

Plasma Levels: Normal levels in plasma range from 3.6 to 4.8 mmol/L.
Distribution and Function: The principle intracellular cation, yet also crucial for extracellular fluid. Influences muscle activity, especially in cardiac muscles. Plays a role in acid-base balance.
Metabolic Function: Essential for metabolic functions like protein synthesis, glycogenesis, and glycogenolysis.

Nervous system and cardiac symptoms: Central nervous system symptoms and cardiac symptoms in the form of bradycardia and poor heart sounds occurring.
Peripheral circulatory collapse and cardiac arrest: Peripheral vascular collapse and cardiac arrest may follow.
Other Symptoms: Mental confusion, numbness, weakness in respiratory muscles, and paralysis in extremities.

Chronic Diseases and Malnutrition: Chronic diseases with malnutrition.
Gastrointestinal Losses: Gastrointestinal losses (vomiting, diarrhea).
Adrenal Cortex Overactivity: Overactivity of the adrenal cortex (Cushing's syndrome).
Diuretic use: Use of diuretics like acetazolamide and chlorothiazide.

Muscle weakness, irritability, and paralysis: Muscle weakness, irritability, and paralysis are key symptoms.
Tachycardia: Tachycardia also accompanies hypokalemia.

Distribution: Predominantly stored in bone and teeth (99%).
Intracellular Calcium: 1% of calcium in intracellular locations, mainly mitochondria and endoplasmic reticulum.
Extracellular Calcium: 0.1% of calcium in extracellular fluid (plasma calcium levels 9-11 mg/dL).

Primary Hyperparathyroidism: Primary hyperparathyroidism.
Secondary Hyperparathyroidism: Secondary hyperparathyroidism (in renal failure).
Vitamin D Toxicity: Vitamin D toxicity.
Tumors Producing PTH-related Proteins: Tumors producing PTH-related proteins.
Bone Metastasis: Bone metastasis.

Spectrophotometer: Measures the amount of light absorbed by a sample, crucial for determining mineral concentrations.
Routine Automated Biochemistry Analyzers: Automated machines processing large volumes of samples, reducing errors and time for analysis.
Blood Tests: Tests using blood samples to measure amounts of minerals.
Red Blood Cell Tests: “Gold standard” for detecting mineral deficiencies.
Urine Tests: Quantitative analysis of minerals in urine samples. Tests can determine mineral deficiency or toxicity.

Formula: Concentration (C_test) = (Absorbance (A_test) / Absorbance (A_standard)) × Concentration (C_standard)

Warm-up: Warm up the instrument for 15 minutes.
Set Wavelength: Set the wavelength appropriate for the sample.
Wipe Cuvette: Wipe the reference solution cuvette with tissue paper.
Place Cuvette: Place the reference solution cuvette into the sample holder. Close the cover.
Zero Absorbance: Set absorbance to zero.
Replace With Standard/Sample: Remove the reference cuvette, and add standard (check its cuvette). Add sample cuvette (check its cuvette).
Read Absorbance: Read and record the absorbance.
Calculate Concentration: Calculate the sample concentration using the formula.