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Mycophenolate sodium (Myfortic) is an enteric-coated formulation of the immunosuppressant therapy mycophenolic acid. We report a case of diffuse mouth ulceration in a patient treated with Myfortic presenting recurrence after another dose of drug.We report the case of a 26-year-old female patient with systemic lupus erythematosus, initially treated with corticosteroids and mycophenolate mofetil, but which was stopped because of varicella-zoster dissemination and leucopoenia. She consulted for mouth ulcers occurring two weeks after the introduction of Myfortic. There were no signs of opportunist infection or lupus activity. Mucosal ulcerations disappeared when Myfortic was stopped. Several weeks later, the patient presented recurrence of mouth ulcerations after another treatment of Myfortic.Myfortic is a new enteric-coated formulation of mycophenolic acid developed to reduce gastrointestinal upset associated with Cellcept. In certain cases, Cellcept toxicity can present as a number of oral ulcerations. Direct toxicity is involved in these cases. This side effect has never been described with Myfortic. In our case, the distinctive characteristic is that the patient was never treated with Cellcept without mucosal toxicity despite equivalent systemic mycophenolic acid exposure.

A primary antiphospholipid syndrome is a very rare cause of adrenal haemorrhage.A 51 year-old man presented with a unilateral adrenal haemorrhage, enhanced by the prescription of Synacthène during the 4 days that preceded. There was no adrenal deficiency but the immunological control revealed the presence of anti-phospholipid antibodies. After 2 years of follow-up, adrenal controls have not shown any underlying tumour or endocrine insufficiency.Adrenal involvement is described in the anti-phospholipid syndrome and may present in the form of adrenal deficiency in the case of occasionally only microscopic bilateral haemorrhages. Furthermore, Synacthène is known to induce adrenal haemorrhages although this complication remains rare. Moreover, any unilateral adrenal haemorrhage requires subsequent follow-up for several months or even years in order to eliminate any underlying tumour and to control the absence of any adrenal deficiency if the involvement is bilateral.

Henoch-Schonlein purpura is one of the most frequent systemic vasculitis in children. In adults, muscle involvement is extremely rare and not very well characterized. We report a case of Henoch-Schonlein purpura with severe skin and renal involvement in witch multiple intramuscular haematoma leaded to severe anaemia. Histological examination confirms the muscle localization of the disease.A 68 years old man treated by oral anticoagulation for multiple venous thrombosis, was admitted with necrotic vasculitis of the skin, abdominal pain and segmental IgA glomerulopathy. The diagnosis of Henoch-Schonlein purpura was rapidly made and intensive steroid therapy started. After rapid improvement, a haemorrhagic shock due to voluminous intramuscular haematoma was diagnosed by MRI. Histological examination of the muscle, confirms the localization of the disease.Intramuscular haematomas are very uncommon in Henoch-Schonlein purpura. There are usually a consequence of muscular immune complex vasculitis. In our patient, high dose corticosteroid was not unable to control the disease.

Pulmonary diseases during the course of generalised amyloidosis are principally represented by tracheobronchial involvement and diffuse parenchymal localizations.The authors report the case of a 66-year-old woman presenting with pleural amyloidosis in the context of generalised amyloidosis. Thoracoscopy performed in the investigation of recurrent transudative pleural effusions found evidence of an inflamed parietal pleura with areas of calcification. Pleural biopsies confirmed amyloid infiltration pleural ossification. Talc pleurodesis was performed.The authors' conclusion is that, meeting an unexplained pleural effusion even transudative during the course of a generalised amyloidosis, the thoracoscopy is the diagnosis key test as it allows moreover a pleural pleurodesis to be performed.

Alpha interferon is increasingly used in the treatment of malignancies and viral hepatitis. Renal involvement after its use consist in more cases on proteinuria. We report one case of acute renal failure without nephrotic syndrome but with tubulointerstitiel infiltration by mononuclear cells in 65 old man who had before interferon therapy 151 mumol/l of serum creatinine. Interferon was administrated for digestive carcinoid neoplasia and bone and liver metastasis. Outcome was improvement of renal function after withdrawn of interferon, dialysis and steroid treatment.

5-aminosalicylic acid (5-ASA) used for the treatment of inflammatory bowel disease is known to induce chronic interstitial nephritis (CIN). However, the frequency of occurrence and the spectrum of severity of 5-ASA-induced CIN are not known. In this paper, we report a new case of CIN induced by 5-ASA in a patient treated for about 7 years for a Crohn disease. After that 5-ASA was discontinued and prednisone therapy started, renal function improved partially. About 30 observations of CIN induced by the use of 5-ASA in patients treated for inflammatory bowel disease have already been published. None were published in patients treated for other diseases such as arthritis rheumatism. The review of the literature suggests that the prognosis is poor and correlates with the duration of treatment, the cumulative dose and the level of renal impairment at diagnostic. We believe that the control of the renal function in patients treated by 5-ASA must be regular and prolonged.

Angiotensin II (AII) acts by 2 types of receptors: the ATI receptor which mediates its actions on vasoconstriction, renin (inhibition) and aldosterone (stimulation) secretions, cellular proliferation and angiogenesis and the non-AT1 (often called AT2) receptors. Mainly expressed in the embryon these latter may favor cellular differentiation and recruitment of collateral circulation. Angiotensin converting enzyme inhibitors (ACEI) decrease the synthesis of All and therefore the stimulation of both receptor types whereas AT1-receptor antagonists (AT1RA) block only the stimulation of these latter and increase the stimulation of AT2 receptor since they increase the production of All secondarily to the inhibition of the feedback of renin secretion by All. Experimentally ACEI and AT1RA decrease angiogenesis and cellular proliferation and favor cellular differentiation which could explain the protective effect of ACEI against cancer suggested recently in a Scotish study. Despite of their common suppressive effect on angiogenesis AT1RA may better than ACEI protect against ischemic events specially the cerebral ones because they favor the rapid recruitment of collateral circulation. This has been demonstrated for losartan in case of abrupt ligation of the carotid in the gerbil since its previous administration protects against fatal cerebral ischemia whereas its previous administration with enalapril abolishes this protection. These data may explain why, in the CAPP trial, captopril which has prevented more effectively diabetes occurrence could not be proved superior to diuretics and/or betablocker in the prevention of myocardial infarction and specially of strokes for which exist on the contrary a suspicion of a lower protection. Therefore a comparative trial between AT1RA and ACEI in the prevention of stroke recurrence should appear as a priority for Public Health and Pharmaceutical Industry Authorities.

The respective contribution of sex, type of nephropathy, degree of proteinuria, blood pressure, protein and sodium daily intake, lipid profile, protidemia, hemoglobinemia, acidosis and CaPO4 product on the rate of renal failure progression is debated. The link between these parameters and the decrease of creatinine clearance, delta Ccr (according to Cockroft) was assessed in uni and multivariate analysis in a population of 49 patients (26 men, 23 women; age 60 +/- 15 years, weight 73 +/- 15 kg) selected out of 173 presently treated hemodialysis patients on the basis of availability of a quarterly follow-up for two years before starting dialysis. The patients were advised a moderate protein and salt restriction which could be retrospectively assessed (on urinary excretion of urea and sodium) at respectively 0.82 g/kg/day and 6.5 g/day. The two years delta Ccr was 14 +/- 14 ml/min. It was not different in men and women (specially when expressed in % of initial value). This decrease in Ccr was neither significantly different in glomerular disease (17 +/- 8, n = 14), diabetic nephropathy (12 +/- 6, n = 7), nephroangiosclerosis (15 +/- 8, n = 5), interstitial nephritis (12 +/- 10, n = 14), and PKD (11 +/- 12, n = 9). Patients with antihypertensive drugs (n = 42) had a faster progression than those without drugs (n = 7): delta Ccr = 15 +/- 14 vs 7 +/- 7 ml/min (p0.05) in spite of comparable blood pressure but with higher proteinuria. Linear regression of delta Ccr with the initial and two year averaged values of the quantitative parameters showed a significant positive link for both values with cholesterol, hemoglobin and proteinuria and a negative one with protidemia. A positive link was observed with the initial value of bicarbonate and the two year mean of diastolic and mean blood pressures. No link at all was observed with urea and Na excretion, CaPO4 product and triglycerides. Multiple regression disclosed a significant link only for protidemia (negative with both initial and two years averaged value), diastolic BP (only for the two year averaged value and hemoglobinemia (for the initial value). When the patients were classified according to a threshold value of their protidemia, DBP, hemoglobinemia, and cholesterolemia those with the combination of two risk factors of progression (pro-tidemia66 g/l, DBPor = 90 mmHg, hemoglobinemia11 g/dl, proteinuria3g/d, CT5 mmol/l) had a significantly greater decrease of Ccr than those with the three other combinations at the exception of the association of low protidemia with DBP.1. diastolic hypertension and low protidemia are the two most important factors predicting progression of renal failure; 2. a predictive synergy was furthermore pointed out between on one hand low protidemia and diastolic hypertension and on the other hand proteinuria and cholesterol; 3. on the contrary, anemia attenuates progression linked to low protidemia, diastolic hypertension, proteinuria and high cholesterol.

The authors present of case of a 61-year-old man suffering from cholesterol emboli, in whom transoesophageal echocardiography revealed complex atheromatous lesions of the thoracic aorta. There is growing emphasis, at the present time, on the concept of triggering factors with the multiplication of endovascular radiological investigations, the more widespread availability of cardiac surgery and the use of anticoagulants and fibrinolytics. The prognosis is poor, treatment is only palliative and preventive measures are therefore essential.

We report a series of 27 patients included on the basis of either thrombotic microangiopathy (TMA) at renal histology (13 cases) or, in the absence of histology, non-immunological hemolytic anemia with schizocytes and thrombopenia (14 cas). The etiopathogenic treatment consisted in the administration of antiagregating agents (in all patients except 3 of group I because of the severity of thrombopenic), corticosteroids (1 case), intravenous immunoglobulins (2 cases) fresh frozen plasma (FFP) without plasma exchange (PE) in 7 cases and PE with FFP in 13 patients. According to the 6 months outcome, 4 groups were considered I: death due to neurological damage; II: chronic hemodialysis; III: partial renal recovery; IV: complete renal recovery.a/Patients with neurological complications have poor prognosis in spite of minor renal involvement and use of PE whose indication is validated in these cases. b/When renal involvement predominates, accelerated hypertension is linked to arteriolar or mixte type of TMA, exposes to an increased risk of hemorrhagic complications of the renal biopsy (4 out fo 5) which questions the usefulness of such biopsy (group II). c/TMA may precede cancer. It has per se a favorable outcome even when metastases are already present, warranting aggressive treatment.

Duplex-scan is widely used for arterial stenosis diagnosis. Its role in detection of renal artery stenosis remains controversial (2, 17, 19, 28). The aim of this study was to determine retrospectively if duplex-scan is accurate for diagnosis of renal artery stenosis. During 36 months, 764 patients had a renal artery examination with duplex-scan: 90 patients had also renal arteriography. Duplex-scan was feasible in 95% of cases (excess bowel gas or major obesity gave to duplex-scan incomplete results in four patients upon 90). Ninety-three per cent of patients had hypertension; 20% had renal failure; 61% had obstruction of coronary, carotid artery or lower limb arteries. Nineteen patients among 86 had also an intravenous renal arteriography. We compared duplex-scan with venous angiography and intra-arterial arteriography. Duplex-scan criteria for stenoses were: a maximal systolic velocity (MSV) above 180 cm/s for detection of 60% to 79% stenoses and a MSV superior to 300 cm/s for detection of 80% to 99% stenoses. Global results showed a good sensitivity 59/64 (92%) and specificity 112/117 (96%) for duplex-scan. Duplex-scan is accurate for diagnosis of renal artery stenosis in a selected population.

Rapidly progressive glomerulonephritis (RPGN) is rarely associated with macroscopic polyarteritis nodosa (PAN), as seen in this series of 7 out of 235 patients. The clinical symptoms of PAN were as follows: myalgias 6; fever 1; arthralgias and mononeuropathy multiplex 5; cutaneous vasculitis 3; arterial hypertension 4, 3 of which were malignant. The mean proteinuria was 2.7 g/24 h; creatininemia 458 microM/l; microscopic hematuria was present in 4 of the 7 patients; only 1 patient was anuric. Markers of hepatitis B virus were absent in all cases. Arteriography revealed microaneurysms and renal infarcts in 6 patients and distal arterial stenosis in one. Renal biopsies from all 7 patients demonstrated extracapillary glomerulonephritis, which was associated with tubulointerstitial fibrosis in one. Necrotizing vasculitis lesions were associated in 5 cases. Immunofluorescence was positive in 5 cases. The association of RPGN and PAN exists and may be underestimated due to the lack of systematic angiographic examinations during RPGN and renal biopsies in PAN patients with renal involvement.

To evaluate the examination of urine erythrocytes with a contrast phase microscope for the etiological diagnosis of haematuria (erythrocytes10/mm3 of non centrifuged urine) the charts of 84 patients with haematuria were reviewed. A nephrological origin had been established with certainty in 56 cases with a renal biopsy and an urological origin was also established with certainty in 28 cases thanks to appropriate radiological, endoscopical and pathological examinations. The morphological criteria of the erythrocytes deformation were those of Birch and Fairley but the quantitative criteria of these authors (either 80 or 100%) were found to be of no value. By successive approaches the threshold of 20% of deformed erythrocytes was selected and found to be the best criterion for diagnosing glomerular hematuria: the sensitivity of the test is then 73% and its specificity 60%. As these results were relatively modest, conditions which decrease the percentage of deformed erythrocytes were excluded to improve the sensitivity, such as macroscopic haematuria and also examinations made during the 6 hours following furosemide administration whereas conditions which increase the percentage of deformed erythrocytes and which are easily diagnosed such as urinary infections, lithiasis and renal insufficiency associated with an uropathy were excluded in order to improve the specificity. Then the examination has a sensitivity and a specificity of 90% which makes it clinically relevant, authorizing a wait and see attitude in case there is an isolated microscopic haematuria of glomerular type.

Between 1 January 1976 and 31 December 1986, primary glomerulonephritis was histologically diagnosed in 319 patients, living in a region of 675,000 inhabitants at the time of renal biopsy. The prevalence of primary glomerulopathy was 0.4/1000 inhabitants. The annual incidence was determined during two 5 year periods: period A (1976-1980) and period B (1981-1985): they were, respectively, 3.4 and 4.5 for 100,000 inhabitants. Berger's focal glomerulonephritis was the most common (30 p. 100) and its incidence was increasing. In contrast, membranoproliferative and acute glomerulonephritides were sharply decreased (almost disappeared), while membranous glomerulonephropathies and glomerulopathies with minimal glomerular lesions or proliferative forms with crescents increased. All primary glomerulonephritides were more prevalent in men and their frequencies increased with age. Our findings lead to the following conclusions: a) the low prevalence and incidence of primary glomerulopathies (3 times less than in other published studies) probably reflect the under medicalization of our region and the attractiveness of neighbouring metropolis, rather than a real decrease in the disease; b) the quasi- disappearance of acute and membranoproliferative glomerulonephropathies and the high incidence of IgA glomerulonephropathies suggest that their pathogenetic associations with infections sensitive to antibiotics are different; c) the increased frequency of membranous glomerulonephropathy and the glomerulopathy with minimal glomerular lesions in aged subjects is most likely due to their polymedication.

The decrease of blood pressure and the increase of plasma renin activity (PRA) after oral administration of captopril was evaluated in 104 consecutive hypertensive out-patients in whom the morphology of the renal arteries and parenchyma was assessed thanks to an intravenous digitalized angiography. Twenty five of these patients were excluded because of a natriuresis less than 50 mmol/24 h or non discontinuation of their treatment; 50 of these patients were classified as essential hypertension, 12 had renovascular disease (10 unilateral stenosis 2 of which significant; 2 bilateral significant stenosis); 9 had unilateral small kidneys (4 significant). The significance was ascertained on the PRA in the renal veins and/or the decrease of hypertension after surgery. The decrease of blood pressure after captopril was not different between the various groups. The increase after captopril of PRA was higher in unilateral significant lesions. However the highest post captopril PRA value was found in the essential hypertension group so that renovascular diseases could not be screened by higher post captopril PRA values. However taking into account that these latter were decreasing with age, a better discrimination of significant unilateral disease was possible in the hypertensive patients above 40 years of age. Furthermore once the diagnosis of unilateral kidney disease is established by radiological investigation, the captopril test allows to predict unilateral hypersecretion of renin with a sensitivity of 100% and a specificity of 78%.the captopril test does not allow to screen the non selected hypertensive patients for an efficient radiological investigation by intravenous digitalized angiography but may help to select the patients with unilateral renal disease for the renal venous PRA evaluation.

After a protein load, the glomerular filtration increases to a maximum called maximal filtration capacity (MFC). The difference of this value with that observed in the fasting state defines the functional renal reserve (FRR). Fifty oral protein loads have been performed in 16 controls (13 adults and 3 children) and 31 patients with kidney disease or hypertension (22 adults, 9 children, 3 tests being performed twice). The load consisted in the adults of 80 g of various proteins. In the children the load consisted in the 100% of the protein intake recommended of the whole day. The urinary samples were made hourly during the 5 hours following the beginning of the meal. The MFC was not always observed during the 2 hours following the end of the meal. However the mean of the clearances measured during these 2 hours allowed an acceptable evaluation of the FRR in 42 out of 50 cases and had the advantage to reduce the errors linked to incomplete bladder voiding. In the adult controls the mean of hourly determined MFC is 156 +/- 27 ml/min, the mean of the clearances measured on the 2 hours following the meal is 136 +/- 21 ml/min and the fasting clearance 96 +/- 22 ml/min. The FRR is null in all patients with a nephropathy with a fasting clearance below 40 ml/min. It is modest or null in patients with acquired or congenital solitary kidney. Three out of five patients with proteinuria have MFC and FRR higher than the mean of the patients with comparable fasting clearances but without proteinuria suggesting that proteinuria is associated with a hyperfiltration state.

To assess whether betablockers (BB) would better control blood pressure than central antihypertensive drugs (CAD) clonidine or alpha methyldopa in hypertensive patients during exercise, comparable triangular ergometric bicycle exercises were performed by the same patients while their hypertension had been controlled at rest either with CAD or BB. Blood pressure, heart rate and blood lactate before and during exercise were compared in II patients treated with metoprolol and CAD, and in 12 other patients treated with atenolol and CAD. Systolic and diastolic blood pressure on exercise were significantly lower with BB than with CAD. Heart rate and rate-pressure product were always lower with BB than with CAD. Blood lactate increase was greater with BB than with CAD. The work capacity was greater with atenolol than with CAD, but comparable between metoprolol and CAD.

After confirming hypercalcemia by 3 successive measurements of the total plasma calcium corrected for a plasma protein concentration of 72 g/l, which excludes spurious hypercalcemia due to dehydration, the physician orientates the aetiological diagnosis bearing in mind that primary hyperparathyroidism PHPT is the cause of 85 p. 100 of all asymptomatic forms of hypercalcaemia whilst overt or occult malignancy is the main cause (60 p. 100) of symptomatic forms of hypercalcaemia with PHPT responsible for 20 p. 100 of cases. Other causes, including drug toxicity with Vit D, calcium, Vit A, lithium, thiazide and aluminium hydroxide, sarcoidosis, hyperthyroidism, Addison's disease, pheochromocytoma and familial endocrine disorders are much rarer. Nevertheless, these rarer causes must be excluded on the clinical history and examination followed by radiological (chest X ray, plain abdomen X ray, bone X rays) and simple biological tests. The latter and/or scans tests should also help in a rapid diagnosis of metastatic carcinoma and multiple myeloma, so that the major diagnostic problem is to distinguish primary HPT from occult malignancy. This problem is greatly facilitated by reliable assays of C terminal or medium PTH rather than renal CAMP which is increased in 80 p. 100 of occult malignancies. When PTH assays is unavailable or unreliable Dent's hydrocortisone suppression test may be useful as a fall in'serum calcium is associated with occult malignancy in 70 p. 100 of cases and non-suppression is associated with PHPT in 91 p. 100 of cases. Discriminant analysis of the usual biochemical parameters may be helpful in this differential diagnosis and is accurate in about 90 p. 100 of cases. However, the association of PHPT and malignancy is also possible and not fortuitous.

In order to determine the effect of beta-blocking agents on secretions of parathyroid hormone and calcitonin, 9 patients with renal failure were given single doses of propranolol (a blocker of the beta 1 and beta 2 receptors) or an equivalent amount of metoprolol (a beta 1 selective agent). Propranolol causes a decrease of plasma parathyroid hormone (p less than 0.02) as well as of calcitonin (p less than 0.05) whereas metoprolol has no effect on the plasma levels of these hormones. These findings suggest that parathyroid tissue and thyroid C cells have receptors that are exclusively of the beta 2 type which are modulating the secretion of parathyroid hormone and calcitonin.

Tienilic acid (250 mg/day) was compared with chlorothiazide (500 mg/day) in 25 hypertensive patients in a randomized cross-over study (2 periods of 2 months). Mean supine arterial pressure was lower with tienilic acid than with chlorothiazide (106 +/- 3 vs 111 +/- 3 mm Hg, p less than 0.05) whereas no difference could be noted in body weight, natriuresis and plasma renin activity. Glucose tolerance tests were altered in the same fashion. Serum cholesterol (234 with tienilic acid and 239 mg/dl with chlorothiazide) and serum triglyceride levels (178 with tienilic acid and 179 mg/dl with chlorothiazide) were not different. Serum urate concentrations were lower with tienilic acid (4.8 mg/dl) than with chlorothiazide (7.8 mg/dl) whereas fractional excretion of urate was much higher with tienilic acid (17 +/- 2%) than with chlorothiazide (7 +/- 2%). Thus, the only metabolic advantage of tienilic acid over chlorothiazide is its hypouricemic effect which warrants long term studies to evaluate its vascular prognostic significance.

The authors review the various techniques of intravenous arteriography before an excretory urogram and discuss their role in the etiological diagnosis of hypertension. Detection of renovascular disease classically implied Seldinger arteriography, with its limited indications, because of side effects and cost. This classical approach should now be systematically replaced by the visualization of renal arteries during the intravenous pyelography procedure which appears to be a method more effective, as well as less expensive and hazardous. The pyelogram wash-out should still be performed when the visualization of the renal arteries is poor because of its value in the screening for renovascular hypertension. Furthermore, when a renal artery stenosis is clearly defined, the wash-out of the pyelogram should also be performed because of its prognostic value. As the classical approach for the etiological diagnosis of hypertension, this technique has limited indications. It is indicated in severe hypertension in the young, when medical treatment does not control blood pressure satisfactorily or when renal failure progresses rapidly. Furthermore, this technique allows a non traumatic follow up of operated or dilated stenoses.

A 59 year-old male developed the nephrotic syndrome in the course of squamous-cell lung carcinoma with metastases. Renal biopsy disclosed amyloid deposits. Immunofluorescence was positive with an anti-SAA antiserum. Amyloidosis complicates exceptionally lung tumors, despite extremely high serum levels of SAA in this type of malignancy. This infrequency shows that determinants other than high SAA serum levels are necessary to create tissue amyloid deposits.

The cost of the systematic radiological examination of 100 hypertensive patients in the search of renovascular hypertension reaches 118 330 F, for the classical approach based on selecting the indications of the Seldinger arteriography on the urographic signs and even 164 950 F when these indications are broadened. The systematic examination of 100 hypertensives by the combined intravenous arteriography and pyelography costs 108 240 F when only one film is taken and 120 910 F when 6 films are taken. The effectiveness for the diagnosis of the 11 renovascular diseases present in 100 hypertensive patients, is measured by the recognition of 8.6-9.1 of them by the classical approach and 10.4-10.9 by the combined intravenous arteriography and pyelography. The effectiveness for the diagnosis of the 2,3 cases of renovascular hypertension present in 100 hypertensive patients is measured by the recognition of 1.8 -1.9 of them by the classical approach and 2.1-2.27 by the combined IV arteriography and pyelography. The cost of finding a patient with curable renovascular hypertension is respectively 51 543 F and 53 264 F with the routine intravenous arteriography according to the number of films and 65 738 and 86 815 F for the classical approach according to wether the indications of the Seldinger arteriography have purely urographic or also clinical basis. In conclusion, the combined intravenous renal arteriography and urography is a method more reliable and less expensive to diagnose renovascular disease and hypertension than the classical approach selecting the seldinger arteriography on the urographic and clinical data. Furthermore, this technic prevents arterial catheterism complications and allows a non traumatic follow-up of the non operated stenosis which may threaten the life of the kidney, as well as the operated or dilated ones.

The authors review recent experimental and human data concerning the potential physiological and pathophysiological role of 24,25 (OH)2D3, the dihydroxylated metabolite of vitamin D which is synthetisized with preference over 1,25 (OH)2D3 in organisms that have been replenished with vitamin D. For the major known effects of vitamin D such as stimulation of intestinal absorption and bone resorption of calcium and phosphorus, 24,25 (OH)2D3 is less effective than the 1,25 (OH)2D3 metabolite and consequently of lesser physiological importance. Some recent in vitro experiments have shown, however, that 24,25 (OH)2D3 intervenes in the stimulation of proteoglycan synthesis, inhibition of PTH, vitamin A and heparin induced resorption, whereas 1,25 (OH)2D3 does not. Although there is controversy as to its direct inhibitory effect on secretion of PTH, it seems to act with 1,25 (OH)2D3 to prevent hyperplasia of parathyroids in vitamin D deficient chicken. From a pathophysiological point, the presence of 24,25 (OH)2D3 seems vital to allow normal bone formation and mineralisation and possibly to counteract excessive bone resorption.