- Discussion:
- is a type of
metabolic bone disease in which the essential problem is a lack of available
calcium or phosphorus (or both) for mineralization of newly formed osteoid;
- children w/
rickets & adults w/ osteomalacia present w/ similar findings;
-
etiology of rickets and osteomalacia:
-
hyperthyroid induced osteopenia:
-
chronic use of anticonvulsant medication:
- deficiency states:
-
vitamin-D deficiency: (strict vegetarians or an extremely low fat diet);
-
gastrointestinal and bilary causes;
-
renal osteodystrophy
-
fibrous dysplasia or neurofibroma:
- osteomalacia & rickets are rare osteoendocrine or neuroendocrine manifestations
of fibrous dysplastic or neurofibromatous dz;
-
anatomic changes in rickets and osteomalacia:
- anatomical and pathological changes differ according to age of patient and the severity of the disorder;
- rickets affects the growing skeleton & thus affects both the epiphyseal plates as well as the bones of children;
- osseous changes in osteomalacia are similar to those in children but are much less evident
because adult skeleton is metabolically less active;
- Clinical Manifestations:
- pts generally complain of easy fatigability, malaise, and bone pain;
- pain is diffuse and poorly localized and is accompanied by a general tenderness of bones;
- frx in an elderly individual that is thought to be the result of
osteoporosis may
be first sign of osteomalacia, & these patients must be evaluated carefully;
- all symptomatic elderly patients should be screened for occult disease;
- bizarre complaints may give impression that patient has mental aberration;
- muscular weakness is often seen in severe cases;
- proximal muscle weakness may be evident & pt may haveT-burg gait;
- Radiographs:
- Looser's zones:
- osteoid seams are insufficiency types of stress frx which are commonly
seen in patients with osteomalacia;
- they are more common in adults than in children;
- patients may have findings of osteomalacia / renal osteodystrophy such as decreased mineralization, coarsened
texture of the bones, "rugger-jersey" appearance of spine, and, occasionally, bowed long bones;
- most of these patients have chronic renal disease;
- Histologic examination:
-
biopsy:
- biopsy is frequently necessary to provide diagnosis, which allows assessment of the
number and thickness of osteoid seams per unit area;
- look for wide osteoid seams;
- there is less mineralized trabecular & cortical bone per unit volume of bone;
- tetracycline labeling helps confirm decreased mineralization of osteoid seams;
-
stress frx:
- unmineralized areas (also called Looser's zones or pseudofractures) are occasionally
seen roentgenographically;
- these zones are caused by rapid resorption & slow mineralization, are generally
perpendicular to bone cortex;
- if stress frx occurs, it may be surrounded by a collar of callus;
-
osteoid seam:
- osteoid seams in osteomalacia are wider than seam found in other diseases;
- diff dx: widened osteoid seams may be found in:
-
rickets;
- osteomalacia;
-
hyperparathyroidism;
-
fibrous dysplasia;
- bone-forming tumors;
- Laboratory Aspects: Osteomalacia:
-
hypocalcemia:
-
hypophosphatemia:
- phosphorus level is low or very low depending on type of osteomalacia, except in
renal osteodystrophy;
-
renal osteodystrophy;
- phosphorus level is invariably high & calcium level will be quite low;
-
alk phos:
- usually elevated in all forms of osteomalacia (except
hypophosphatasia);
- References:
Massive osteolysis.
