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Pathogenesis of bioch.changes vit. D impaired ca & ph. Absorpt from intest + ph.reabsorp. By renal tubules hypocalcemia + hypophosphatemia + hyperphosphaturia. Hypocalcemia stmulates parathyroid gl. Parathormone mobilisation of ca from bone to Bl.& thus serum ca is corrected & to normal. However, Ph. reabs. by renal tub. is more impaired exagerated hyperphosphaturia& hypophosphatemia . Some exceptions: 1-Serum ca my be : A-if this physiological hyperparathyrodism fails to occur . B- in late stages with depletion of bone ca. C- during tt of rick. after shock therapy when deposition of ca & ph in bone occurs in expense of serum ca. D- as a complic. For G.E. complicated by acidosis. 2-serum alkaline phosphatase may be normal & not in rick. If it is associated with protein depletion ( atrophic rickets ) Clinical manifestations of early rickets: 1- Biochemical changes: Especially high alkaline phosphatase levels are earliest manifest. of rick. 2- Radilogical changes: They occur before appearance of clinical manifest. 3- clinical manifest. : A- symptoms : head sweating, irritability, anorexia & conistipation. Their pathogemesis is not fully explained but it may result from disturbed function of autonomic nervous system. B- signs: 1-craniotabes: it is a ping pong bone feeling of skull bones when compressed by fingers indicating their softness & thinness it tends to be localised over occipital & post. part of parietal bones. It is rarely present before 3 months of age & disapp. at age of 5-6 ms. up to 1yr. 2- Rossary chest. Manifestations of advanced rickets : *Symptoms: delayed sitting, standing, walking & teething or bone deformeties. *Signs: 1-skeletal manifest.: 1-Head : 1- enlargement & asymmetry. 2- bossing at frontal & parietal eminences 3- some parts of vault of skull may be menbraneous. 4- box-like appear.of head or caput quadratum. 5- depression at root of nose. 6-delayed closure of ant. fontanell 7-delayed eruption of teeth . 2- Chest: 1-Rosarry beads: these are small palpable swellings at costochondral junctions sparing 1st & 2nd ribs as they are not 2- Harrison’s sulcus: it is a transverse groove at lower chest wall at costal insertion of diaphragm produced by dragging effect of diaph. during resp. movem. on soft bones of chest . 3- longtudinal sulcus: it is a vertical groove behind rossary beads resulting from compression of ribs by atmospheric pressure at their weakest points. 4- pigeon chest: it is result of protrusion of sternum. 5- flaring of lower ribs with eversion of costal margins Consequences of chest deformities : 1-limitation of chest capacity for expansion susceptibility to chest infection & atelactasis. 2- spleen & liver may be palpable due to downard displacement by deformed thorax & also due to hypotonicity. 3- Abdomen: 1-abd. Protrusion is nearly a constant finding in infantile rick. 2- palpable liver & spleen . 3- umblical hernia . 4-Pelvis (Rachitic pelvis ): 1-contracted inlet : due to forward projection of promontory of sacrum produced by exageration of lumbar lordosis 2- oultet contraction:due to forward projection of tip of coccyx. 5-Extremities : 1- enlargement of ends of long bones: 2- pathological fractures . 3- Marfan’s sign It is a transverse groove felt by palpation at lower ends of long bones mostly over tibia just above medial malleolus giving imperssion of double epiphy.due to abn. prolif. of cartilage at 2 different areas producing 2 elevations with a groove in () . 4- Deformities of long bones:it affects upper more than lower limbs in crawling infants & vice versa in standing & walking infants. 5- Deformities of joints: due to hypotonia of ms. & laxity of ligaments e.g. genu recurvatum, genu varum& genu valgum. 6- Spine : kyphosis, scolisis & kyphoscliosis with compensatory exaggeration of lumbar lordosis are often present . II- Muscular manifest. 1: hypotonia: may be due to hypophosphatemia III- Neurological manifest. A-early: in form of sweating, anorexia, irritability&constipation b- late: in form of tetany. D.D. of rickets: 1-Causes of delayed walking: I- C.N.S. causes : mental retard., microcephaly, hydrocephalus, cerebral palsy, post-encephalitic& postmeningetic, post-kernicteric encephalopathy, cong. Malform., trauma. II- Spinal cord lesions:Sp.compression, pott’s dis., trauma, spina bifida, poliomylitis, spinal muscular atrophy dis., transverse myelitis. III- Peripheral n. & myoneural junction lesions: Peripheral neuritis, infectious polyneuropathy IV- Ms. Dis.: Muscular dystrophy, rickets, cong. hypotonia, polymyositis, hypokalemia, P.C.M, ch. Debilitating dis. V- Bone Dis.: Osteogenesis imperfecta, chondrodystrophy 2- Causes of craniotabes: Rickets, hydroceph., cong. $, osteogenesis imperfecta, chondrodystrophy, prematurity, hypervitaminosis A. 3- causes of depressed bridge of nose: rickets, mongolism, cretinism, hypertelorism, cong. $., familial, ch. Hemolytic anemias, hydroceph. 4- causes of rosary chest: rickets (rounded due to rach. metaph. ) scurvy (angular due to sublaxation of sternal & costal parts of ribs), chondrodystrophy, marasmus. 5- causes of delayed closure of ant. fontanel : rickets, hydroceph., mongolism, cretinism, chondrodystrophy, osteogenesis imperfecta, prematurity, I.C.T. Complications of rickets 1-Respiratory complic. : Chest infections with or without atelactasis are frequent & are due to: A:chest deformily expansn vital capacity. B- hypotonia of the resp.ms.with weakness of the cough reflex. 2- G.I.T.complic.: A- Alternating diarrh. & conistip. due to hypotonia of intest. & abd. ms. B- secondary bact. infection . 3- Others : A- anemia : due to iron or associated second. Infection. B- tetany C- skeletal deformities. D- dwarfism. Treatment of infantile rickets : I- Prophylactic ttt.: exposure to sun rays, prophylactic administration of vit. D, administ. of vit.D to pregnant or lactating mother, supplmentation by vit.C 25 mg/day ( as vit.C is acidic.which help solubelity & absorption of ca II-Curative ttt.: A- Specific therapy. Vit.D2 is given in a dose of 1500 – 5000 I.U./day or shock therapy 600000 I.U. once monthly for 3 successive months . B- Adjuvant therapy : Adeqate ca& phosph. Intake, vit. especially vit. B complex, vit. C & iron , exposure to ultraviolet sunrays better from 5-8 a.m. & 3-5 p.m. Non-vit.D deficiency rickets •Def.: rickets not responding to usual doses of vit.D. * Types: primary type ( hypophosphatemic, hypocalcemic ), renal, hepatic, onchogenic, associated with anticonvulsant drugs. Diagnostic aids : I- History : age of onset beyond 2-3 yrs, lack of hist. of vit.D , hist. of adeq. Vit.D therapy, +ve family hist., urinary troubles as polyuria, ch.hepatic troubles as liver failure . II- Clinical Exam.: evidence of a renal dis., evidence of a hepatic dis., hepatosplen. sugg.of metabolic dis. as fanconi synd., mental retard. + ocular manif. sugg. of lowe’s synd. III- Investigations: serum ca, ph, alkaline phosph., urine for amino acid, phosphaturia glucosuria, calcuria & PH, blood for PH, electrolytes, ocular exam. (slit lamp) for cystine crystals & cataract , renal function tests, liver function tests. Vit. D resistant hypophosphatemic rick. *Etiology : due to inherited disability of kid. To reabsorp phosphates due to defective hydroxylation of vit.D. in kid. *Genetics: sex-linked dominant occuring more in females. *Clinical picture: bone deformities especially in L.L., retarded linear growth, no affection of general health, no involvement of chest& head bones, no hypotonia, tetany due to persistent hypophosphatemia . *Biochemical changes: hypophosphatemia, hyperphosphaturia, normal serum ca. *Treatment: massive vit. D therapy 50000 – 150000 I.U./ day untill healing or toxicity appears., oral phosphates 0.5- 1.5 gm / d. during infancy & 1.5-3 gm/day after infancy, osteotomy for bone defects. Vit.D resistant hypocalcemic rick. Etiology: due to inherited inability of renal tubules to reab. Ca+ ca abs. From intestine 2nd hyperparath. Genetics : A.R. Bioch changes : serum ca. , normal phosphate, aminoaciduria Ttt: massive vit.D therapy 10000-40000 I.U. / d., corrected osteotomy for bone defects Renal rickets it is either a- renal glomeular rick. B- renal tubular rick. Renal glomeular rick (renal osteodystrophy) Def: alterations in skeletal growth & remodling that occur in children with chronic renal disease because of abnormalities in mineral & bone metabolism. Etiology : cong. malform. of kid., obestructive uropathy, ch. pyelonephritis, ch. glomerulonephritis. Pathology: inability of kid. to excrete ph phosphates rexcreted in gut& combine with ca ca level sec. Hyperparathyrodism osteodystrophy due to stimul. of osteoclasts bone resorption. Diagnosis :rachitic manifest. & dwarfism with renal sympt. as polyurea, anaemia & hypertention + manif. of osteoprosis. Biochemical changes: hyperphosphatemia, ca, bl. urea & alkaline phosphatase. ttt : manag. of kid. conditions & correct acidosis, diet high in ca & low in ph with oral administ.of Aluminium hydroxide or a cation exchange resin to remove ph., vit. D 25000-250000 I.U./day, dihydrotachysterol 0.1-0.2 mg/day, partial excision of parath.gl. B- Renal tubular rickets : I- Fanconi syndrome Def.: synd. Charact. by defect in proximal renal tubules with reabsorption of glucose, ph, a.a, Na. K, bicarbonate & uric acid. Etiology : inherited autosomal recessive, cystinosis, glycogenosis, lead pois. Clinical picture: polyuria, polydepsia, growth retard., uric acid stones, metabolic acidosis, hypokalemia in form of ms. weakness, abd. pain & distension, rickets. Biochemical changes: aminoaciduria, hyper phospphaturia, glucosuria Na, k, bicarb. uric acid in urine. Cong. Hypophosphatasia.: def.: ch. familial dis. (autoso. Recess.) charact by inborn dficiency of alkaline phosphatase Clinical picture: a- In neonatal period : soft skeleton, severe deformities, globular skull,irritability, anorexia, vomiting, constipation, cyanosis or death. b- During infancy: the symptoms appear gradually between 1-6 months. Anorexia, vomiting, constipation, failure to thrive, bouts of unexplained fever. The scull shows separation of sutures & wide bulging ant. Fontanel. Rachitis rosaries & enlargement of the ends of long bones. C- during childhood: orthopedic deformities as genuvalgum, knock knees, defective gait, marked dental caries& failure to gain weight. Blood chemistry : serum ph is normal, serum ca may be normal or increased, alkaline phosphatase diminished. ttt. : cortisone may be of value, vit.D has no therapeutic effect. Hper vitaminosis D causes: ingestion of excessive amounts of vit.D: a- giving therapeutic big doses. b- increase of the dose by anxious parents c- substituting a concentrated form of vit.D. clinical picture: hypotonia, anorexia, constipation, polyuria, polydipsia, renal failure, pallor, hypercalcemia & hypercalcuria, dehydration. X-ray : metastatic calcification, dense metaphyseal line associated with decrease of density of the shaft. ttt.: discontinue vit.D, low ca diet, correct dehydration, cortisone, aluminium hydroxide.