Nephrocalcinosis: a rare presenting manifestation of primary Sjögren’s syndrome

Renal involvement in primary Sjögren’s syndrome (pSS) is not uncommon. Autoimmune tubulointerstitial disorders and distal renal tubular acidosis (dRTA) account for majority of the cases of renal involvement. While dRTA may precede the onset of sicca syndrome in pSS, nephrocalcinosis as a presenting manifestation of pSS is rare. Here, to emphasize the need for initiating investigations for pSS in any patient presenting with nephrocalcinosis due to dRTA, we report a 21-year-old woman presenting with nephrocalcinosis long before pSS was objectively diagnosed.     

Nephrocalcinosis and hypokalemia in a patient with primary Sjögren’s syndrome

Clinically significant renal involvement is uncommon in primary Sjögren’s syndrome, amid which tubulointerstitial disorders, distal renal tubular acidosis (dRTA) particularly, account for the majority. Conversely, Sjögren’s syndrome comprises at least half the patients presenting with renal tubular acidosis. While underlying dRTA itself is an important cause of nephrocalcinosis and urolithiasis, nephrocalcinosis is rarely a presenting feature of primary Sjögren’s syndrome. I report a 41-year-old female contracting nephrocalcinosis and hypokalemia as complications of primary Sjögren’s syndrome with dRTA, hereby to emphasize the importance of alkali therapy.     

Nephrocalcinosis: a rare presenting manifestation of primary Sjögren’s syndrome

Abstract

Renal involvement in primary Sjögren’s syndrome (pSS) is not uncommon. Autoimmune tubulointerstitial disorders and distal renal tubular acidosis (dRTA) account for majority of the cases of renal involvement. While dRTA may precede the onset of sicca syndrome in pSS, nephrocalcinosis as a presenting manifestation of pSS is rare. Here, to emphasize the need for initiating investigations for pSS in any patient presenting with nephrocalcinosis due to dRTA, we report a 21-year-old woman presenting with nephrocalcinosis long before pSS was objectively diagnosed.     

Genetische Ursachen von St?rungen des S?ure-Basen-Haushalts

Disturbances of the acid-base homeostasis caused by a reduced capacity of renal acid excretion or by a renal loss of bicarbonate are summarized under the term renal tubular acidosis. The common feature is a normal anion gap acidosis as determined by arterial blood gas analysis in combination with an almost always inadequate high urinary pH (>?5.5). The spectrum of the underlying defects differs with respect to abnormalities of serum potassium concentration, presence of nephrocalcinosis or nephrolithiasis, inner ear deafness, growth retardation, rickets and polyuria. Common hereditary forms of RTA are grouped into four defined clinical types: type I RTA with disturbed proton secretion in distal nephrons (distal dRTA), type II RTA with diminished bicarbonate reabsorption in proximal nephrons (proximal pRTA), type III RTA or mixed RTA with disturbance of both proximal bicarbonate reabsorption and distal proton secretion and type IV RTA with insufficient aldosterone response of distal nephrons (RTA with hyperkalemia).     

Symptomatic renal tubular acidosis (RTA) in patients with systemic lupus erythematosus: an analysis of six cases with new association of type 4 RTA

OBJECTIVES: We have analysed the association between different parameters of renal tubular acidosis (RTA) with clinical and laboratory parameters in patients with systemic lupus erythematosus (SLE). METHODS: Review of hospital database records between 1978 and 2003 revealed six SLE patients with RTA. Correlations and comparisons were done by Spearman rank correlation coefficient and the chi(2) test. RESULTS: Four patients had hypokalaemia (type 1 RTA) and two patients had hyperkalaemia (type 4 RTA). Three patients with type 1, but no patients with type 4 RTA, had medullary nephrocalcinosis. The majority of SLE patients with distal RTA (type 1 and type 4) had nephritis with proteinuria. No seronegative SLE was noted, and all patients were negative for anticardiolipin antibodies. There was a noticeable trend of higher serum potassium levels with increased SLE Disease Activity Index (SLEDAI; P < 0.1) and nephritic manifestation (haematuria, P < 0.1). The mean SLEDAI scores were 11.75 and 27.5 for type 1 and type 4 RTA patients, respectively. CONCLUSIONS: When present in patients with SLE, classic distal RTA (type 1) is the most common. In particular, we report here for the first time two cases of type 4 RTA in SLE patients with higher SLEDAI scores than patients with type 1 RTA. Medullary nephrocalcinosis or renal urolithiasis has not been found in our patients with type 4 RTA. Higher serum potassium levels seem to be associated with higher SLEDAI scores and more severe nephritic manifestations in patients with distal RTA.     

Nephrocalcinosis in Sjögren's syndrome: a late sequela of renal tubular acidosis

Abstract. Sjögren's syndrome (SS) is an autoimmune exocrinopathy that develops into systemic autoimmune disease in 25% of patients, leading to general complications, one of which is kidney involvement. It presents mainly as interstitial nephritis, disclosed by hyposthenuria, distal renal tubular acidosis (RTA) and diabetes insipidus. We here describe five cases of SS with type-1 RTA (hyperchloraemic metabolic acidosis with an anion gap and alkaline urine pH) who developed nephrolithiasis, nephrocalcinosis and renal insufficiency. Hypercalciuria due to acidosis was the main nephrocalcinosis-prone factor in four patients; four subjects displayed diminished renal concentrating capacity, and two had hypokalaemia.     

Low serum erythropoietin—a strong diagnostic criterion of primary polycythaemia even at normal haemoglobin levels

Summary Estimations of serum erythropoietin level by enzyme immunoassay (EIA) kit were made in 42 patients with primary polycythaemia, and in a comparison group consisting of 41 patients with secondary polycythaemia and 47 patients with idiopathic erythrocytosis. The majority of patients with primary polycythaemia were undergoing treatment by venesection and therefore had Hb levels in the normal range at the time of erythropoietin estimation. In primary polycythaemia, 64% of the first samples taken from each patient were below the reference range for serum erythropoietin in normal individuals. When two samples were taken from each patient 72% had low values in one or both samples. In the comparison group, analysis of those patients who had two samples taken showed only one individual with secondary polycythaemia and none with idiopathic erythrocytosis who had a serum erythropoietin level below the reference range. The finding of low serum erythropoietin in patients with primary polycythaemia, even when Hb levels are normal due to venesection, is of high diagnostic specificity (few false positive results) and useful diagnostic sensitivity (28% false negative results). It is proposed that future diagnostic criteria of primary polycythaemia should include the finding of a serum erythropoietin level below the lower limit of normal in at least one of two serum samples taken on different occasions.     

RENAL AND PANCREATIC CALCIFICATION IN RHEUMATOID ARTHRITIS WITH SJOGREN'S SYNDROME

We describe a female patient who developed seropositive rheumatoidarthritis (RA) at the age of 12 years. After 10 years her diseasewas complicated by Sjogren's syndrome (SS) and distal (type1) renal tubular acidosis (RTA). Seven years later she was notedto have nephrocalcinosis. At the age of 32, investigation ofa short history of weight loss and abdominal pain revealed abenign gastric ulcer and chronic calcific pancreatitis. We believe she is the first patient with RA and SS in whom complicatingrenal and pancreatic calcification have been reported. Her caseemphasizes the good prognosis of type 1 RTA in SS and suggeststhat pancreatic involvement may be more common than clinicallyapparent. KEY WORDS: Rheumatoid arthritis, Sjögren's syndrome, Renal tubular acidosis, Pancreatic calcification     

Nephrocalcinosis: initial manifestation of primary Sjögren's syndrome

INTRODUCTION: Nephrocalcinosis is a rare complication of chronic tubulointerstitial nephritis observed in primary Sj?gren's syndrome. It can precede subjective sicca symptoms. OBSERVATION: We report the case of a 50-year-old woman who presented with a primary Sj?gren's syndrome. The first symptoms appeared 10-years-ago while she was affected with a nephrocalcinosis. CONCLUSION: Autoimmune investigations for Sj?gren's syndrome should be initiated in any patient presenting with nephrocalcinosis and distal renal tubular acidosis.     

Heterogeneity of erythropoietin-dependent erythrocytosis: case report in a child and synopsis of primary erythrocytosis syndromes

To investigate the pathogenesis of polycythaemia in a child with isolated, primary erythrocytosis, we measured serum erythropoietin activity and in vitro erythroid progenitor cell responsiveness to erythropoietin. Unstimulated erythropoietin activity was markedly elevated (1.8 IU/ml), and isovolaemic phlebotomy induced a four-fold increment above this level. In contrast to findings in our index case with this syndrome, normal erythroid colony growth patterns were present in patient marrow cultures. The primary mechanism of polycythaemia in this individual is similar to that reported in the index case: an inappropriately elevated regulatory set point for erythropoietin production. Since an additional defect of progenitor cell hypersensitivity to erythropoietin is not always present, we conclude that abnormalities at single or multiple sites of the erythropoietic regulatory axis may occur in primary erythropoietin-dependent erythrocytosis.     

Renal abnormalities in sickle cell disease

Many renal structural and functional abnormalities have been associated with sickle cell disease. The patients have an impaired urinary concentrating ability but an intact diluting capacity. There are defects in both urinary acidification and potassium excretion, although overt metabolic acidosis and hyperkalemia occur infrequently. Proximal tubular function is supranormal, as manifested by increased reabsorption of phosphate and increased secretion of creatinine. The former results in mild hyperphosphatemia, while the latter causes substantial overestimation of the glomerular filtration rate (GFR) by creatinine clearance. Both GFR and renal plasma flow are increased in young patients with sickle cell disease, but prostaglandin inhibitors decrease the GFR. The GFR progressively decreases with increasing age. Proteinuria, and even nephrotic syndrome, are relatively frequent; the most common renal lesion in children is focal glomerular sclerosis, which may be associated with progressive deterioration in renal function. Glomerular hyperfiltration has been implicated in the pathogenesis of the glomerular lesions, as well as in the development of renal failure. In patients with end-stage renal disease, both hemodialysis and kidney transplantation have been successful. Recurrent hematuria is a relatively common problem in patients with sickle cell disease. The bleeding usually remits spontaneously, but occasionally requires therapy with aminocaproic acid. Papillary necrosis may occur, and is thought to result from medullary ischemia.     

The pathogenesis of hyperchloremic metabolic acidosis associated with kidney transplantation

The mechanism of persistent hyperchloremic metabolic acidosis developing after kidney transplantation was investigated in six patients. In five patients in whom acidosis failed to lower the urine pH below 5.5, an infusion of sodium sulfate also failed to lower the urine pH. Neutral phosphate infusion failed to increase the urine minus blood (U-B) carbon dioxide tension (pCO₂) difference normally in these patients. This abnormal response to both maneuvers indicates the presence of a tubular defect for distal hydrogen ion secretion. In the remaining patient, spontaneous acidosis lowered the urine pH below 5.5 and increased the U-B pCO₂ normally with the administration of phosphate, demonstrating that this patient's distal capacity for hydrogen secretion was intact. The plasma aldosterone level was low in this patient, and thus he had the acidification defect characteristic of aldosterone deficiency. Hyperkalemia developed in two patients; both were aldosterone-deficient, and they had a low fractional potassium excretion in response to stimulation with sodium sulfate or acetazolamide. In all but one patient, who lost his kidney to accelerated rejection, chronic rejection developed. Homogeneous deposition of complement (C3) along the tubular basement membrane was found in three patients. Our data suggest that a secretory type of distal renal tubular acidosis can be an early sign of the immunologic process that leads to chronic rejection.     

Renal potassium wasting in distal renal tubular acidosis: role of aldosterone.

The pathogenesis of renal potassium wasting and hypokalemia in classic renal tubular acidosis (type 1 RTA) remains uncertain. The prevailing theory is that K(+)-Na+ exchange is stimulated due to an inability of the distal tubule to establish a normal steep lumen-peritubular H+ gradient. We encountered a 42-year-old woman with type 1 RTA associated with Sj?gren's syndrome, in whom renal potassium wasting and hypokalemia persisted despite sustained correction of systemic acidosis with alkali therapy and increased intake of potassium. In addition, plasma renin activity was markedly increased and the serum aldosterone level was upper-normal despite the hypokalemia. Increased intake of sodium resulted in suppression on the serum aldosterone and correction of renal potassium wasting and hypokalemia. This case shows that secondary hyperaldosteronism, possibly due to an impairment of sodium conservation in the distal tubule, may contribute to the loss of potassium from the distal tubule even after the correction of acidosis.     

Hyperkalemic distal renal tubular acidosis and selective aldosterone deficiency. Combination in a patient with lead nephropathy

A patient with chronic renal failure, a strong history of moonshine abuse, and excessive urinary lead excretion had clinical and laboratory measurements compatible with combined hyperkalemic distal renal tubular acidosis and the syndrome of selective aldosterone deficiency. Extended treatment with fludrocortisone acetate, 0.1 to 0.2 mg/day, did not ameliorate acidosis or restore potassium excretion.     

Idiopathic erythrocytosis — additional new study techniques suggest a heterogenous grou

Abstract: 25 patients with idiopathic erythrocytosis (absolute increase in red cell mass without conventional criteria of primary polycythaemia or known underlying cause) have been further studied for evidence of primary or secondary polycythaemia. Additional non-conventional criteria used were: platelet distribution width, platelet nucleotide ratio, serum erythropoietin, clinical evidence of ischaemic vascular disease and erythroid culture variables in serum-free system. All had been used in an earlier study in score form to assist in the diagnosis of primary polycythaemia. These patients were also newly assessed for the presence of hypoxia (supine oximeter values, history suggestive of sleep apnoea), for renal lesions and for splenic enlargement (impalpable) by ultrasound or computerized tomography. 7 patients had erythroid culture scores suggesting primary polycythaemia but the addition of non-culture criteria did not result in any scores more strongly predictive of primary polycythaemia. Supine oximeter values <92% suggested hypoxaemia as the mechanism of polycythaemia in 3 patients in whom it had not previously been suspected. Some splenic enlargement (impalpable) was demonstrated in 6 patients, only 1 of whom had erythroid culture scores suggesting primary polycythaemia. 12 patients had confirmed, raised erythropoietin levels. We conclude that idiopathic erythrocytosis refers to a heterogenous group of patients. Features of primary or secondary polycythaemia may be demonstrated in some of them by additional new study techniques. The raised erythropoietin values found in half the patients were unexpected.     

Osteomalacia revealing Sjögren's syndrome: a case report

INTRODUCTION: The most common renal disease in Sj?gren's syndrome is tubulo-interstitial nephritis, responsible for tubular acidosis in around 20 % of patients. Osteomalacia exceptionally occurs as the first manifestation of a renal tubule disorder due to a Sj?gren's syndrome. EXEGESIS: We report a case of a 20-year-old woman with tubular acidosis induced osteomalacia secondary to primary Sj?gren's syndrome. Improvement was obtained with bicarbonates, vitamin D, calcium and high-dose steroid therapy. CONCLUSION: During Sj?gren's syndrome, osteomalacia can complicate the distal renal tubular acidosis. In spite of the rare cases of osteomalacia revealing Sj?gren's syndrome, this auto-immune disease must appear in the list of the aetiologies of osteomalacia.     

Autonomous erythropoietin induced erythrocytosis.

Erythrocytosis in a young Sinhalese man is described. The patient was known to have had a raised Hb and PCV for at least 10 years. Subsequent investigations failed to support the diagnosis of polycythaemia vera or to reveal a cause for secondary polycythaemia. Blood erythropoietin values were raised, but no cause for inappropriate secretion could be identified. Although there was no evidence of erythrocytosis in the family, the findings in this patient appear to be those of a condition which has been called familial polycythaemia. The spleen was unusually large and was associated with hypersplenism and thrombocytopenia. Problems of diagnosis and management are described. Phlebotomy appears to be the treatment of choice, with a regimen of regular venesection for the control of symptoms due to hyperviscosity and vascular occlusion.     

Autonomous Erythropoietin Induced Erythrocytosis

Erythrocytosis in a young Sinhalese man is described. The patient was known to have had a raised Hb and PCV for at least 10 years. Subsequent investigations failed to support the diagnosis of polycythaemia vera or to reveal a cause for secondary polycythaemia. Blood erythropoietin values were raised, but no cause for inappropriate secretion could be identified. Although there was no evidence of erythrocytosis in the family, the findings in this patient appear to be those of a condition which has been called familial polycythaemia. The spleen was unusually large and was associated with hypersplenism and thrombocytopenia. Problems of diagnosis and management are described. Phlebotomy appears to be the treatment of choice, with a regimen of regular venesection for the control of symptoms due to hyperviscosity and vascular occlusion.     

Polyuric prerenal failure after reduction from high to normal dietary intake of sodium

In a patient with renal amyloidosis secondary to chronic urinary tract infection with nephrotic syndrome, polyuric acute renal failure developed after reduction from a high to a normal dietary intake of sodium and was reversed by salt replacement therapy. As documented by functional and morphological studies, the patient had a marked defect of tubular sodium reabsorption at the proximal site and along the ascending limb of Henle's loop, a distal tubular unresponsiveness to aldosterone, and severe tubulointerstitial damage in the medulla. We propose that the sodium dietary reduction in conjunction with severe tubular dysfunction and hypovolemia due to nephrotic syndrome is responsible for this unused form of polyuric acute prerenal failure.     

Disorders of distal nephron function

In this review, the distal nephron is considered to be that portion of the renal tubule commencing with the thick ascending limb of the loop of Henle and ending with the papillary collecting duct. The collecting duct, including its subdivisions in the cortex and medulla, originates from a different embryologic anlage than more proximal nephron segments, which may explain its morphologic and functional dissimilarities from the thick ascending limb and the distal convoluted tubule. This review summarizes selected aspects of the physiology of the distal nephron, with particular emphasis on the physiology of distal nephron transport of sodium, potassium, chloride and hydrogen ion. The pathophysiologic features of the following disorders of distal nephron function are reviewed: (1) pseudohypoaldosteronism, a heterogenous group of disorders in which the signs and symptoms are suggestive of aldosterone deficiency, but in which aldosterone levels are supernormal and administration of exogenous mineralocorticoid is not ameliorative; (2) pseudohyperaldosteronism (Liddle syndrome), a familial disorder in which the clinical manifestations closely resemble those resulting from an aldosterone-producing adenoma of the adrenal gland (primary aldosteronism), but in which the measured rate of aldosterone secretion and excretion is greatly subnormal; (3) Bartter syndrome and related syndromes of renal potassium wasting; (4) type 1 renal tubular acidosis (classic, distal); (5) type 4 renal tubular acidosis (hyperkalemic). Reference citations are generally to articles reporting recent advances in these areas and to review articles that contain comprehensive bibliographies.