Date post: | 03-Apr-2018 |
Category: |
Documents |
Upload: | jaya-prabha |
View: | 233 times |
Download: | 0 times |
of 19
7/28/2019 rickets and osteomalacia-
1/19
A 40 year old male , a known case of epilepsy presentedwith a 4-month history of generalized muscular
discomfort, particularly in her shoulders, present at rest.The symptoms were not worse in the morning and therewere nonspecific relieving factors. Her weight wasstable.
On examination she exhibited mild proximal weakness
in both arms and legs, but no muscle tenderness and thereflexes were preserved. There was no temporal artery orscalp tenderness, and the remainder of the examinationwas unremarkable.
7/28/2019 rickets and osteomalacia-
2/19
Subsequent investigation demonstratedhaemoglobin 10.9 g/dL,ESR 16mm/h, plasma
glucose (postprandial) 7.6mmol/L, glycatedhaemoglobin 5.6%, plasma urea andelectrolyteswithin normal limits,
plasma calcium 7.4mg/dl(N 8.5-10.5),phosphate
2.5mg/dl(N 4.5-6.5) and plasma alkalinephosphatase 198IU/L (normal
7/28/2019 rickets and osteomalacia-
3/19
What is the most likely explanation for her symptoms
and what other causes should be considered?
7/28/2019 rickets and osteomalacia-
4/19
This patient's presentation with myalgia associatedwith a combination of mild hypocalcaemia,hypophosphataemia and elevation of alkalinephosphatase is strongly suggestive of Osteomalasia.
7/28/2019 rickets and osteomalacia-
5/19
Rickets and osteomalacia are conditionscharacterized by pathological defects in bone matrix
mineralization. Rickets refers specifically toosteomalacia, where the defect occurs in growingbone.
The aetiological factors are diverse, but the end
result is an increased quantity of unmineralizedbone matrix (osteoid).
RICKETS AND
OSTEOMALACIA
7/28/2019 rickets and osteomalacia-
6/19
RICKETS &
OSTEOMALACIA
Def.: reduction in bone mineralization !
7/28/2019 rickets and osteomalacia-
7/19
The conditions may arise in three distinct
situations:
Deficiency or abnormal metabolism of vitamin D
Phosphate depletion
Chronic metabolic acidosis.
aetiology of
osteomalacia
7/28/2019 rickets and osteomalacia-
8/19
Vitamin D deficiency is numerically by far themostimportant cause of osteomalacia (or rickets): itleads to acombined deficiency of calcium andphosphorus. There is intestinal malabsorption of
calcium and, to a lesser extent Phosphorus. Secondaryhyperparathyroidism results from the fall in plasmacalcium, and the ensuing phosphaturia accelerates thephosphate deficiency.
7/28/2019 rickets and osteomalacia-
9/19
Lack of vitamin D is often due to a combination of poor exposure to
sunlight and dietary deficiency. The elderly are particularly at risk. The reason for this is multifactorial and incompletely understood, but
dietary deficiency of vitamin D and calcium, together with binding ofcalcium by the phytate contained in chapati flour, may contribute. Inaddition,deeply pigmented skin generates less vitamin D3 inresponse to a given amount of ultraviolet exposure, an dthis may bedisadvantageous in temperate climates.
Vitamin D deficiency may complicate fat malabsorption from anycause.
Finally, calcium deficiency enhances the rate of degradation of 25(OH)D
in the liver, further exac-erbating the shortage of vitamin D and itsmetabolites. abnormality of the 1,25(OH)2D receptor in target tissues(vitamin D-dependent rickets type II).
7/28/2019 rickets and osteomalacia-
10/19
Phosphate depletion is a less common cause ofrickets than deficiency or altered metabolism ofvitamin D. It arises as a result of a reduced maximalcapacity for renal tubular phosphate reabsorption. This
may either be inherited as an X-linked recessivecharacteristic (vitamin D-resistant rickets, X-linkedhypophosphataemia) or occur aspart of Fanconi'ssyndrome - a more generalized hereditary oracquired renal tubular defect typified by
aminoaciduria and glycosuria (p. 1057).Rarely, excessive ingestion of antacids may restrict
intestinal phosphate absorption to the point whereclinically important phos-phate depletion, and evenosteomalacia or rickets, may appear.
7/28/2019 rickets and osteomalacia-
11/19
Chronic metabolic acidosis, usually resulting from
renal tubular disorders, may lead to rickets orosteomalacia. The bone lesions usually healsatisfactorily following treatment to correct theacidosis.
7/28/2019 rickets and osteomalacia-
12/19
7/28/2019 rickets and osteomalacia-
13/19
In children, failure of bone mineralization gives
rise to classic bone deformities, which include
widening of the metaphyses, prominence ofcostochondral junctions (socalled 'rickety rosary'),and varus or valgus abnormalities of the knee
joints. The bones are painful and statural growthis reduced.
In adults, bone pain and tenderness are the mostprominent features. A characteristic proximalmyopathy may develop, and is more common incases due to vitamin D deficiency.
Clinical features
7/28/2019 rickets and osteomalacia-
14/19
Biochemical In osteomalacia due to deficiency or abnormal metabolismof vitamin D, investigations typically demonstrate a low
normal plasma calcium (leading to secondary hyper- parathyroidism), a low plasma phosphate due to phospha- turia as a result of increased PTH secretion, and a raisedalkaline phosphatase indicating increased numbers of osteoblasts . Vitamin D deficiency may be confirmed by measurement of 25-
hydroxyvitamin D in plasma. X-linked hypophosphataemia (vitamin D-resistantrickets), on the other
hand, is characterized by normocal-caemia, hypophosphataemia, andlittle or no alteration in
plasma alkaline phosphatase level.
Investigation
7/28/2019 rickets and osteomalacia-
15/19
RICKETS, OSTEOMALACIA
XRAY FINDINGS:
RICKETS
Thickening and widening ofphyses,
Cupping of metaphysis,
Wide metaphysis,
Bowing of diaphysis,
Blurred trabeculae.
http://www.emedicine.com/cgi-bin/foxweb.exe/makezoom@/em/makezoom?picture=/websites/emedicine/radio/images/Large/13201benttibiaUM.jpg&template=izoom2http://www.orthoteers.co.uk/Nrujp~ij33lm/Images7/rickets1.jpg7/28/2019 rickets and osteomalacia-
16/19
RICKETS, OSTEOMALACIA
XRAY FINDINGS:
OSTEOMALACIA
Loosers zones - incomplete
stress # with healing lackingcalcium, on compressionside of long bones.
Codfish vertebrae due topressure of discs
Trefoil pelvis, due toindentation of acetabulaestress #s
http://www.emedicine.com/cgi-bin/foxweb.exe/makezoom@/em/makezoom?picture=/websites/emedicine/radio/images/Large/13605ruggerM.jpg&template=izoom2http://www.orthoteers.co.uk/Nrujp~ij33lm/Images7/osteomalacia1.jpg7/28/2019 rickets and osteomalacia-
17/19
Occasionally a bone biopsy may be needed(following
double tetracycline labelling) to confirm a diagnosisof
osteomalacia whhen biochemical investigations areequivocal. This is particularly the case when
seeking possible treatable factors in elderly patientswith decreased bone density.
Histological
7/28/2019 rickets and osteomalacia-
18/19
Dietary vitamin D deficiency is treated by oral replace-
ment of vitamins D2 or D3 in physiological quantities(500-1000 units/day). This can conveniently be given as combinedcalcium with vitamin D tablets.Alternatively,a single i.m. does of 150 000IU of D2 in oil iseffective prophylaxis and treatment for at least 6 months. Thepossibility of intestinal malabsorption should be borne in mind,and appropriate investigation initiated if necessary.
Osteomalacia associated with anticonvulsant therapyrequires higher doses of vitamin D (3000-6000units/day)unless a change in anticonvulsant is clinicallyfeasible.
Management
7/28/2019 rickets and osteomalacia-
19/19
Treatment of X-linked hypophosphataemia is
generallyunsatisfactory. The logical treatment is with
oral phosphatesupplements, but the doses neededare large and they maybe poorly tolerated because ofgastrointestinal side-effects.Oral phosphate worksbetter when combined with phar-macologicaldoses of vitamin D, or (and probably best)
incombination with 1,25(OH)2D3. When1,25(OH)2D3 orlaOHD3 is given, great care mustbe taken to adjust the dose against the serumcalcium, as hypercalcaemia may easily be induced.
Management