Page 377 - Medicine and Surgery

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Chapter 8: Metabolic bone disorders 373

Investigations Management
Urate levels are often high, although they may fall during The pain of pseudogout is relieved by nonsteroidal anti-
an acute attack. Inflammatory markers (CRP, ESR) may inflammatory drugs, aspiration of synovial fluid and
be raised. Aspiration of joint fluid will demonstrate the intra-articular steroid injection.
negatively birefringent crystals.
Metabolic bone disorders
Management
Acute gout is managed with high dose nonsteroidal anti-
inflammatory drugs. Hyperuricaemia is treated only if Osteoporosis
associated with recurrent gout attacks.
Definition
Non-pharmacological: Weight loss, high-fluid intake,

A disease characterised by low bone mass and microar-
low alcohol, low-purine diet, avoid thiazides and as-
chitectural disruption. It is diagnosed if the race/sex
pirin.
matched bone density falls below 2.5 standard devia-
Pharmacological: Allopurinol, which inhibits xan-

tions from the average young bone density (WHO).
thine oxidase. Excess purines are excreted as xan-
thine rather than uric acid, and the therapy is lifelong.
Incidence
Steroids can be injected into troublesome joints.
Overall 30% of individuals will have a pathological frac-
ture due to osteoporosis.
Pseudogout
Age
Females over 50 and males over 55 years.
Definition
Acrystal arthropathy resulting from calcium pyrophos-
Sex
phate dihydrate (CPPD) deposition in the joints.
2F : 1M
Aetiology/pathophysiology Aetiology
CPPD crystal formation occurs in cartilage located near Bone is continually being remodelled involving reab-
chondrocytes. It is suggested that excessive cartilage py- sorption and synthesis. It is thought that osteoporosis
rophosphate production leads to local crystal formation. results from a long-term slight imbalance between the
Crystals are thought to enter the joint cavity after being two processes. The risk of fractures increases with bone
shed from the cartilage in which they have formed. loss and hence with age. Factors that can affect the re-
modelling balance are as follows:
Sex: Females have a lower bone mass and a high rate of

Clinical features bone loss in the decade following the menopause. This
Chondrocalcinosis may be detected on X-ray in cartilage is largely oestrogen-dependent, early menopause and
without joint disease. Acute joint inflammation resem- ovariectomy without hormone replacement therapy
bles gout most commonly affecting the knee and other predisposes. Gonadal failure and androgen insensi-
large joints. tivity are risk factors for osteoporosis in men.
Age: Age-related bone loss is seen in both sexes; al-

though worse in females, this may be due to decreased
Investigation calcium absorption.
Examination of the joint fluid will demonstrate posi- Genetic factors implicated include the vitamin D re-
tively birefringent crystals. ceptors and collagen genes.