Basic Concepts of Fluid and Electrolyte Therapy

Four common aspects of Ca 2+ disorders deserve a mention here:
Osteomalacia (Rickets in children)
This is due to Vitamin D deficiency caused by lack of exposure to sunlight,
malnutrition, some gastrointestinal diseases which cause fat
malabsorption, and renal disease causing reduced levels of
1,25(OH) 2
D3. It is characterized by typical radiological changes in
bone, low serum Ca 2+ , raised serum PO
2–
4
, elevated alkaline phosphatase
and PTH, and low blood Vit D levels. Treatment is with 0.25-
1 mg of 1 -hydroxycholecalciferol daily and, in some cases, calcium
supplements.
Osteoporosis
This involves not only thinning of bone calcium but also of its protein
matrix. Its causes are multifactorial but include ageing, the
menopause, immobility, calcium deficiency, hypogonadism, etc. It is
diagnosed radiologically and by bone density measurement. It may be
reduced by sex hormone supplements, Ca 2+ and vitamin D, and exercise,
and treated by bisphosphonates.
Hypercalcaemia
Any elevation of serum Ca 2+ should be investigated thoroughly.
Although, in severe cases it may be important to reduce very high levels
of Ca 2+ as soon as possible, the main challenge to the doctor is to
distinguish early between malignant causes e.g. secondary malignancy
in bone or PTH secreting tumours, and more easily curable ‘benign’
causes such as hyperparathyroidism, vitamin D intoxication, sarcoid,
etc. Primary hyperparathyroidism is associated with elevated PTH
levels whereas these are suppressed in secondary malignancy from
non PTH secreting tumours.
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