Osteoporosis: Classification

Densitometric classification of osteoporosis (WHO staging).

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• T-score (T-value) is a statistical measure that indicates the difference of measurement results from the mean value of bone density of young adults (25-40 years) of the same sex. The T-score is expressed in standard deviations (SD) and is crucial for the assessment of fracture risk.

Ringe’s osteoporosis is divided into primary and secondary forms:

Primary or Idiopathic Osteoporosis.

• Infantile and juvenile osteoporosis (rare form that can occur between the ages of 8 and 14).
• Primary osteoporosis type I – adult, postmenopausal osteoporosis.
• Primary osteoporosis type II – senile (age-related) osteoporosis.

Primary osteoporosis type I

This type of osteoporosis predominantly affects women between the ages of 50 and 70. The main cause is believed to be a deficiency of the female sex hormone estrogen, which is triggered by hormonal changes during the menopause (menopause). In this case, the estrogen deficiency causes an increase in various cytokines (messenger substances) that stimulate the osteoclasts (cells that break down bone tissue again), as a result of which the bone substance is continuously broken down. Therefore, this form of osteoporosis is also called postmenopausal osteoporosis.

Primary type II osteoporosis

This type of osteoporosis – also called senile osteoporosis – affects women and men over the age of 70 equally. In this form of osteoporosis, the compacta (outer marginal layer of the bone) is increasingly affected in addition to the cancellous bone (bone tubercles; these give the bone its stability, i.e., its resistance to fracture). Therefore, fractures (bone fractures) of the long bones occur predominantly here. In this disease, also known as senile osteoporosis, vitamin D resistance and vitamin D deficiency occur in old age and lead, among other things, to a reduction in calcium resorption from the intestine. Secondary osteoporosis – which accounts for around 5% of all osteoporoses – affects women and men equally and develops as a result of a pre-existing underlying disease. The consequences are the same as for primary osteoporosis.

Secondary osteoporosis

• Endocrinologically induced osteoporosesHormone deficiency:
  • Hypogonadism (hypofunction of the gonads).
    • Woman and man
    • Anorexia nervosa
    • High performance female athletes
    • Ovarectomy (removal of the ovaries)
  • Growth hormone deficiency (pituitary insufficiency).

  Hormone excess:

  • Hyperthyroidism (overactive thyroid gland).
  • Hypercortisolism (permanent excess of cortisol; Cushing’s syndrome).
  • Hyperprolactinemia
  • Primary hyperparathyroidism (pHPT)
• Other endocrinopathies:
  • Diabetes mellitus type 1
• Complex osteopathies:
  • Nutritional disorders
    • Malabsorption
    • Maldigestion
    • Malnutrition (starvation osteoporosis)
    • Alcoholism
• Renal osteopathy
• Osteoporosis due to neoplastic disease/cancer:
  • Plasmacytoma
  • Paraneoplasia
  • Tumor cachexia
• Osteoporosis caused by inflammatory diseases:
  • Rheumatoid arthritis
  • Inflammatory enteropathies
• Osteoporosis caused by hereditary (genetically determined) connective tissue diseases.
  • Ehler-Danlos syndrome (EDS) – group of diseases caused by a disorder of collagen synthesisdefect in the collagen type I alpha-1 gene.
  • Glycogen storage diseases
  • Homocystinuria (homocystinuria) – metabolic disorders that lead to increased concentrations of the amino acid homocysteine in the blood and homocystine in the urine, resulting in symptoms similar to Marfan syndrome.
  • Marfan syndrome – systemic connective tissue disease, based on a gene mutation; it can be inherited autosomal dominant or occur sporadically (as a new mutation); it is noticeable mainly by tall stature.
  • Osteogenesis imperfecta (OI) – disease of connective tissue characterized by incomplete bone formation with increased bone fragility.
• Mechanically induced osteoporosis:
  • Bed rest
  • Weightlessness
  • Immobilization
• Iatrogenic-medicinal causes: see below “Causes/Medications”.