Calcium Handling

An (very) old video lecture on calcium handling and pathology thereof. Still as relevant now as it was then!

 

Lecture by

Video Duration: 10 minutes

  • Hypocalcaemia
    Created by Nitin Lamba
    General
    Epidemiology

    Total plasma calcium level <2.2mmol/L

    Pathology

    If due to renal failure, hypocalcaemia occurs due to reduced production of activated Vitamin D (leading to less calcium reabsorption in the small intestine) and increased retention of phosphate, by the kidneys.

    If due to hypoparathyroidism, parathyroid glands produce less PTH, which leads to:

    1) Reduced absorption of calcium by the kidneys

    2) Reduced production of activated Vitamin D by the kidneys, leading to reduced absorption of calcium by the small intestine

    Both of the above lead to a decrease in serum calcium levels.

    Top three causes

    Renal Failure

    Hypoparathyroidism, due to parathyroidectomy or autoimmune cause

    Vitamin D deficiency, due to malnutrition or malabsorption (osteomalacia)

    Clinical Features
    Symptoms

    May be asymptomatic.

    If symptomatic,

    1. Perioral paraesthesia
    2. Cramps
    3. Tetany/Carpopedal spasm
    4. Affected vision, due to cataracts/papilloedema


    Signs
    1. Chvostek's sign (twitching of facial muscles following tapping over CNVII in Parotid gland area)
    2. Trousseau's sign (carpal spasm caused by inflation of sphygmomanometer around arm above level of systolic BP)
    3. Prolonged QT interval, potentially causing cardiac arrhythmias
    4. Cataracts/papilloedema


    Investigations
    Cultures

    24 urinary calcium measurement

    Bloods

    Serum calcium

    U&Es (to check if renal disease is present)

    Serum PTH (if low in combination with low calcium --> suggests parathyroid cause; if PTH is high with low calcium --> suggests Vitamin D deficiency)

    Serum parathyroid auto-antibodies

    Serum 25-hydroxy-vitamin

    Imaging

    None

    Scopic/Biopsy

    None

    Functional

    ECG

    Treatment
    Conservative

    Oral Calcium supplements 5mmol every 6 hours

    Medical

    Acute treatment of tetany: 10ml of 10% Calcium Gluconate IV infusion over 10 minutes.

    Maintenance therapy: 1,25 Dihydroxycholecalciferol (activated vitamin D) or 1-alpha-hydroxycholecalciferol (synthetic vitamin D/alphacalcidol)

    Surgical

    None

  • Hypercalcaemia
    Created by Nitin Lamba
    General
    Epidemiology

    Calcium level >2.6mmol/l.

    Prevalence = 1:1000

    Most common in elderly women

    Pathology

    Most common cause is Primary Hyperparathyroidism, usually caused by a Parathyroid Adenoma or Hyperplasia.

    This leads to excessive PTH production, which causes

    1) increased calcium reabsorption in the kidney

    2) increased activation of Vitamin D in the kidney, which in turn increases absorption of Calcium from small intestine

    3) increased osteoclast activity, leading to bone resorption

    All 3 lead to an increase in serum calcium levels

    Top three causes

    Primary Hyperparathyroidism (common!)

    Secondary Bone Metastases (common!)

    Excessive Vitamin D (rare

    Clinical Features
    Symptoms

    Asymptomatic in mild cases

    "Bones, Stones, Groans and Psychic Moans"

    Bone Pain (Osteitis Fibrosa Cystica)

    Stones: Polyuria, Polydipsia (Nephrogenic Diabetes Insipidus), Nocturia, Renal Calculi, Chronic Kidney Disease

    Groans: Abdominal pain, nausea, vomiting, constipation

    Psychic moans: Confusion, Reduced GCS, Fatigue, Muscle Weaknes

    Signs

    Dehydration

    Investigations
    Cultures

    24 hour urinary calcium measurement

    Bloods

    Serum Calcium and Phosphate

    Serum PTH


    Imaging

    None

    Scopic/Biopsy

    None

    Functional

    Protein electrophoresis (if myeloma is suspected

    Treatment
    Conservative

    None

    Medical

    If serum calcium > 3.5, treat as a medical emergency:

    IV Fluids (Normal saline 4-6L over 24 hours and then 3-4L over several days)

    Bisphosphonate

    Treatment of underlying cause

    Steroids useful if due to sarcoidosis

    Calcitonin, Phosphate therapy (hypercalcaemia associated with hypophospataemia

    Surgical

    Surgical removal of parathyroid adenoma (if cause)

    Surgical parathyroidectomy (if due to parathyroid hyperplasia)