Renal tubular acidosis. Three cases with immunoglobulin abnormalities in the patients and their kindreds

Osteomalacia associated with adult Fanconi's syndrome: clinical and diagnostic features

OBJECTIVE

Osteomalacia associated with adult acquired Fanconi's syndrome is thought to result from hypophosphataemia and relative 1,25-dihydroxyvitamin D deficiency. We have followed the clinical and diagnostic features of patients with osteomalacia associated with adult Fanconi's syndrome, with particular emphasis on their responses to treatment with calcium, phosphate and vitamin D.

DESIGN

Retrospective Mayo Clinic case-note review from 1975 to 1994 and prospective follow-up study, combined with literature review.

PATIENTS

Eleven patients (7 male, 4 female) were identified who satisfied criteria for diagnosis of osteomalacia and adult Fanconi's syndrome. Twenty-five additional patients were identified in a literature review from 1954 to the present.

METHODS

Clinical history and physical examination, serum and urine bone and mineral parameter, X-ray radiography and iliac crest bone histomorphometry.

RESULTS

All patients presented with typical symptoms of osteomalacia, including lower extremity or low back bone pain, and all had fractures, pseudofractures, and/or bone demineralization on X-ray radiography. Osteomalacia and Fanconi's syndrome were diagnosed concurrently in 10 patients, whereas osteomalacia preceded diagnosis of Fanconi's syndrome by 5 years in one patient. Pre-treatment bone biopsies in 9 of the 11 patients demonstrated increased osteoid surface, volume and width. In the one patient labelled with tetracycline prior to biopsy, mineralization lag time was prolonged at 111 days (normal 19.2 +/- 1.0 days). Hypophosphataemia, inappropriately low 1,25-dihydroxyvitamin D levels, renal insufficiency, and chronic acidosis due to bicarbonate leak and uraemia, contributed to the osteomalacia in these patients. Secondary hyperparathyroidism was present in two patients. Eight of the 11 patients with osteomalacia associated with Fanconi's syndrome had monoclonal disorders, including multiple myeloma or lymphoma, many of them manifest by light-chain proteinuria. Over a mean patient follow-up period of 46 months (range 1-239 months), patients responded symptomatically to calcium, phosphate, and vitamin D replacement typically within 1-6 months. In 8 patients in whom follow-up data were available, post-treatment serum phosphate and 1,25-dihydroxyvitamin D levels improved in the setting of stable mild renal insufficiency; only one patient developed end-stage renal failure after 20 years, suggesting that these patients do not invariably progress rapidly to renal failure.

CONCLUSIONS

Regardless of the underlying cause, osteomalacia associated with adult acquired Fanconi's syndrome appears to respond well to calcium, phosphate, and vitamin D replacement. These patients do not appear to necessarily require 1,25-dihydroxyvitamin D replacement.

Complete distal renal tubular acidosis in systemic lupus: clinical and laboratory findings

We report two patients with systemic lupus erythematosus (SLE) who were found to have complete (acidotic) distal renal tubular acidosis (DRTA). One patient had nephrocalcinosis and renal magnesium wasting with tetany; the other patient had nephrolithiasis and nephrotic syndrome secondary to membranous glomerulopathy. Both patients had decreased urinary citrate excretion but neither had hypercalciuria. We discuss the association of DRTA with immunologic disorders and the possible role of hypocitraturia in promoting renal calcification in these patients. We suggest that patients with renal calcification be evaluated for DRTA, and that patients found to have DRTA be further evaluated for signs, symptoms, and laboratory evidence of immunologic disorders.

Renal tubular acidosis: its types and role in renal calculosis

In the light of published observations attention is called to the various forms of renal tubular acidosis (RTA), its etiology, pathologic significance, excretion of an "alkaline-persistent" urine in the presence of hyperchloremic acidosis, and to the possible consequences: nephrocalcinosis and renal calculosis. The frequency of incomplete RTA of various causes in calculosis is pointed out. The patient material of the authors and the results of phosphate therapy are presented, stressing the importance of alkalizing therapy and its prophylactic value.

Suppression of leukocyte chemotaxis by human IgA myeloma components

Sera from patients with IgA myeloma suppressed polymorphonuclear leukocyte (PMN) chemotaxis, while generally little or no suppression was observed with sera from patients with IgG myeloma or Waldenstrom's macroglobulinemia. Chemotactic inhibitory activity was not limited to a single chemotactic factor and was equivalent when C5a, bacterial factor, casein, or normal serum were used as chemotactic attractants. No association was noted between the degree of inhibitory activity and the IgA subclass or light chain type. Chemotactic inhibitory activity was found to be directly associated with isolated IgA M components, and similar chemotactic suppression was noted with purified preparations of normal human colostral IgA. By comparison, IgA preparations were most effective in suppressing PMN chemotaxis and had a much lesser effect on monocyte chemotaxis. The mode of IgA chemotactic inhibition was cellular and at least partially reversible after a 37degreesC incubation in the absence of IgA. Some inhibition of PMN random mobility was noted with certain IgA preparations, although such effects did not parallel the degree of chemotactic inhibition. Fractionation of IgA myeloma sera and IgA M components by sucrose density gradient centrifugation showed multiple peaks of inhibitory activity in 10 to 13S fractions. The majority of IgA inhibitory activity was lost after pepsin digestion or sulfhydryl reduction and alkylation of isolated M components. When isolated IgA M components were fractionated on Sephadex G-200, inhibitory activity was associated with the exclusion volume and was abolished by reduction and alkylation procedures which resulted in a conversion of polymeric IgA to monomeric IgA.

Connective tissue lysozyme in health and disease

As the lysozyme story continues to unfold, rheumatic disease is one area where the study of this fascinating protein will be most important. The special biochemical features of lysozyme--its hexosaminidase function, its ability to bring about transglycosylation, its homology to alpha-lactalbumin, and its cationic nature--suggest that the connective tissues may prove to be the key to the understanding of the function of lysozyme. As methods for its accurate measurement become standardized, better data on the activity of the enzyme in various tissues and body fluids, in both health and disease, will be forthcoming. As additional studies are done to ascertain which of the hypothetical functions attributed to lysozyme are of significance in vivo, it will be the student of the connective tissues and the diseases thereof who can be expected to profit most from an udnerstanding of the role of lysozyme in mammalian biology.

High-molecular-weight hydroxyproline-protein in relation to immunoglobulins M (IgM) in human blood serum

The content of the high-molecular-weight protein-bound hydroxyproline (Hyp) and IgM level in the sera of 30 healthy persons and 29 patients showing changes in gamma and/or beta globulin levels was determined. Statistically significant correlations between quantities of these components have been found. On the base of the present results as well as the results of previous studies authors suggest that the high-molecular-weight Hyp-protein contains immunoglobulin of the IgM class.

Fanconi syndrome in adults. A manifestation of a latent form of myeloma

From a review of 17 cases of Fanconi syndrome with Bence Jones proteinuria and myeloma or amyloidosis, including three new cases reported here in detail, there emerges a well defined set of characteristics. In most cases, the diagnosis of Fanconi syndrome preceded the development of myeloma or amyloidosis. Myeloma preceding the development of Fanconi syndrome has not been reported. All the patients had Bence Jones proteinuria, but in some it could be detected only by electrophoresis or immunoelectrophoresis, In the seven cases in which the Bence Jones protein was typed, it was of kappa type. There were no serum protein monoclonal abnormalities. In the bone marrow and renal samples of half of the patients, crystalline cytoplasmic inclusion bodies were present in lymphoplasmacytic elements and renal tubular cells. It is proposed that patients with Fanconi syndrome and Bence Jones proteinuria have a distinct type of plasma cell disorder or variant of the monoclonal gammopathies, characterized by a slow progression of the tumor and by an early phase dominated by the metabolic complications of the renal proximal tubular dysfunction. Adult patients with Fanconi syndrome should be carefully investigated for the presence of Bence Jones protein and a plasmacytic dyscrasia should be excluded.

Multiple immunological abnormalities in a family

The family of a woman with multiple autoimmune diseases has been investigated. Clinical evidence of an autoimmune disorder was detected in two relatives, and five others had serological and immunoglobulin abnormalities. It is suggested that there is an inherited predisposition to develop immunological abnormalities, and that a number of associated autoimmune diseases may develop in families in which this occurs.

Fibrosing alveolitis associated with renal tubular acidosis

The discovery of a case of renal tubular acidosis and fibrosing alveolitis led to the investigation of 19 further patients. Abnormal pulmonary function tests were found in a further four patients with overt renal tubular acidosis and in four out of eight patients with "incomplete" renal tubular acidosis. The response to an ammonium chloride test in seven patients with cryptogenic fibrosing alveolitis was normal. Those patients with a defect of both renal acidification and pulmonary gas transfer had concurrent autoimmune diseases such as Sjögren's syndrome and primary biliary cirrhosis. It is suggested that the renal and pulmonary abnormalities may be part of a systemic disorder capable of affecting many organs. Moreover, hyperglobulinaemia and autoantibodies in these patients further suggests that immunological mechanisms are concerned in the pathogenesis of these abnormalities.

Hyperglobulinaemic renal tubular acidosis: a report of nine cases

Of nine women with hyperglobulinaemic renal tubular acidosis four presented with acidosis and five had the "incomplete" form of the disorder. Seven patients had nephrogenic diabetes insipidus, but none had the Fanconi syndrome. Investigation showed abnormal immunoglobulins and autoantibodies in all nine patients. Diseases coexisting with renal tubular acidosis were Sjögren's syndrome, hyperglobulinaemic purpura, autoimmune liver and thyroid disease, diffuse pulmonary fibrosis, and a peripheral neuropathy. It is suggested that this type of renal tubular acidosis might be due to an autoimmune process.