C3 deposition in renal arterioles in the loin pain and haematuria syndrome

Understanding painful versus non-painful dental pain in female and male patients: A transcriptomic analysis of human biopsies

Dental pain from apical periodontitis is an infection induced-orofacial pain condition that presents with diversity in pain phenotypes among patients. While 60% of patients with a full-blown disease present with the hallmark symptom of mechanical allodynia, nearly 40% of patients experience no pain. Furthermore, a sexual dichotomy exists, with females exhibiting lower mechanical thresholds under basal and diseased states. Finally, the prevalence of post-treatment pain refractory to commonly used analgesics ranges from 7-19% (∼2 million patients), which warrants a thorough investigation of the cellular changes occurring in different patient cohorts. We, therefore, conducted a transcriptomic assessment of periapical biopsies (peripheral diseased tissue) from patients with persistent apical periodontitis. Surgical biopsies from symptomatic male (SM), asymptomatic male (AM), symptomatic female (SF), and asymptomatic female (AF) patients were collected and processed for bulk RNA sequencing. Using strict selection criteria, our study found several unique differentially regulated genes (DEGs) between symptomatic and asymptomatic patients, as well as novel candidate genes between sexes within the same pain group. Specifically, we found the role of cells of the innate and adaptive immune system in mediating nociception in symptomatic patients and the role of genes involved in tissue homeostasis in potentially inhibiting nociception in asymptomatic patients. Furthermore, sex-related differences appear to be tightly regulated by macrophage activity, its secretome, and/or migration. Collectively, we present, for the first time, a comprehensive assessment of peripherally diseased human tissue after a microbial insult and shed important insights into the regulation of the trigeminal system in female and male patients.

Kidney Biopsy and Type IV Collagen Gene Sequencing Fail to Explain Hematuria in Loin Pain Hematuria Syndrome

Introduction

Loin pain hematuria syndrome (LPHS) is a rare clinical syndrome with a reported prevalence of 1 in 10,000. The syndrome is characterized by severe pain localized to the kidney in the absence of identifiable urinary tract disease. Because of an inadequate understanding of the pathophysiology of the disease, the goal of management has been limited to symptomatic pain management. Through detailed phenotype and genotype assessment we sought to identify possible underlying etiologies.

Methods

We completed a chart review, ultrasound imaging, kidney biopsy, and type IV collagen (COL4A3, COL4A4, and COL4A5) gene sequencing in 14 patients with loin pain hematuria recruited from a single center.

Results

Red blood cells and red cell casts were observed within the tubules in 10 of 14 patients. The glomerular basement membrane (GBM) was normal in 11 patients and thickened in 1 patient. Staining for IgA kappa was present in 1 patient. C3 deposition without any inflammation was present in 7 patients. Arteriolar hyalinosis was present in 4 patients and endothelial cell injury was present in 6 patients. No pathogenic COL4A3, COL4A4, or COL4A5 variants were identified.

Conclusion

Conventional histopathology and genetic testing for type IV collagen variants failed to identify the cause of hematuria in 14 patients with LPHS.

Treatment and Management of Loin Pain Hematuria Syndrome

PURPOSE OF REVIEW

Loin pain hematuria syndrome (LPHS) is rare and seldom diagnosed, yet it has a particularly significant impact on those affected. This is a review of the latest and seminal evidence of the pathophysiology and diagnosis of LPHS and presents the typical clinical presentation and treatment options available.

RECENT FINDINGS

LPHS is typically found in young women with characteristic symptoms, including severe recurrent flank pain and gross or microscopic hematuria. The majority of patients will experience crippling pain for many years without effective therapy, often requiring frequent use of narcotic medication. However, the lack of conclusive pathophysiology, in conjunction with the rarity of LPHS, has prohibited the development and trial of definitive treatment options. Nevertheless, in order to combat this rare but severe disease, management strategies have continued to evolve, ranging from conservative measures to invasive procedures. This review presents an overview of the current hypotheses on the pathophysiology of LPHS in addition to summarizing the management strategies that have been utilized. Only 30% of LPHS patients will experience spontaneous resolution, whereas the majority will continue to face chronic, crippling pain. Several methods of treatment, including invasive and non-invasive, may provide an improved outcome to these patients. Treatment should be individually tailored and multi-disciplinary in nature. Further research is required to further elucidate the pathophysiology and develop new, specific, treatment options.

Interventional Approaches for Loin Pain Hematuria Syndrome and Kidney-Related Pain Syndromes

PURPOSE OF REVIEW

Loin pain hematuria syndrome (LPHS) frequently presents with severe chronic pain that poses a clinical challenge. Current treatment approaches are mostly empirical and include a wide range of therapeutic strategies such as physical therapy, local and systemic analgesia, interventional and surgical approaches usually flanked by psycho-behavioral therapy, and other strategies. LPHS often impacts negatively on quality of life particularly in patients who are refractory to treatment.

RECENT FINDINGS

With recent advances in catheter-based treatment approaches and better understanding of the pathophysiology of LPHS, intraluminal renal denervation (RDN) has been proposed as a valuable treatment option for kidney-related pain syndromes. The present review provides a brief overview of the clinical challenges associated with LPHS, highlights recent insights into its underlying mechanisms, and summarizes currently available data on the use of RDN in the context of LPHS and kidney-related pain syndromes. Renal denervation via various approaches including surgical and catheter-based techniques has shown promise in alleviating kidney-related pain syndromes. Randomized controlled trials are now required to better define its role in the management of these conditions.

Neuroimmune Mechanisms in Signaling of Pain During Acute Kidney Injury (AKI)

Acute kidney injury (AKI) is a significant global health concern. The primary causes of AKI include ischemia, sepsis and nephrotoxicity. The unraveled interface between nervous system and immune response with specific focus on pain pathways is generating a huge interest in reference to AKI. The nervous system though static executes functions by nerve fibers throughout the body. Neuronal peptides released by nerves effect the immune response to mediate the hemodynamic system critical to the functioning of kidney. Pain is the outcome of cellular cross talk between nervous and immune systems. The widespread release of neuropeptides, neurotransmitters and immune cells contribute to bidirectional neuroimmune cross talks for pain manifestation. Recently, we have reported pain pathway genes that may pave the way to better understand such processes during AKI. An auxiliary understanding of the functions and communications in these systems will lead to novel approaches in pain management and treatment through the pathological state, specifically during acute kidney injury.

The Complement System in Neuropathic and Postoperative Pain

Certain types of pain are major unmet medical needs that affect more than 8 percent of the population. Neuropathic pain can be caused by many pathogenic processes including injury, autoimmune disease, neurological disease, endocrine dysfunction, infection, toxin exposure, and substance abuse and is frequently resistant to available pain therapies. The same can be said of postsurgical pain, which can arise from uncontrolled inflammation around the wound site. The complement system is part of the innate immune system and can both initiate and sustain acute and chronic inflammatory pain. Here we review the complement system and original investigations that identify potential drug targets within this system. Drugs that act to inhibit the complement system could fill major gaps in our current standard of care for neuropathic pain states.

Loin pain hematuria syndrome

Loin pain hematuria syndrome (LPHS), first described in 1967, is a rare pain syndrome, which is not well understood. The syndrome is characterized by severe intermittent or persistent flank pain, either unilateral or bilateral, associated with gross or microscopic hematuria. LPHS is a diagnosis of exclusion as there still is not a consensus of validated diagnostic criteria, though several criteria have been proposed. The wide differential diagnosis would suggest a meticulous yet specific diagnostic work-up depending on the individual clinical features and natural history. Several mechanisms regarding the pathophysiology of LPHS have been proposed but without pinpointing the actual causative etiology, the treatment remains symptomatic. Treatment modalities for LPHS are diverse including simple analgesia, opioid analgesic and kidney autotransplantation. This review article summarizes the current understanding regarding the pathophysiology of LPHS along with the steps required for proper diagnosis and a discussion of the different therapeutic approaches for LPHS.

Loin pain hematuria syndrome: a psychiatric and surgical conundrum

PURPOSE OF REVIEW

The loin pain hematuria syndrome presents a dilemma with regards to the etiology, as well as the treatment of this rarely seen entity. In view of the increasing frequency of diagnosis, and the question of whether this disorder constitutes a somatoform disorder or a physical disorder remedied through renal autotransplantation we should familiarize ourselves with this condition, so as to clarify its nature.

RECENT FINDINGS

There may be a subset of loin pain hematuria syndrome patients that have a somatoform disorder. Patients appear to have better outcomes with autotransplantation, than with intraureteric capsaicin treatment or renal denervation.

SUMMARY

This paper attempts to provide an overview of the topic and propose further investigation to better determine whether a subset of these patients have a somatoform disorder.

Morphological studies of baseline needle biopsies from living donor kidneys: light microscopic, immunohistochemical and ultrastructural findings

Fifty-seven consecutive living donors (31 women and 26 men aged 20.7-72.3 years, mean 50.6 years) were subjected to needle biopsy during nephrectomy, immediately before removal of the kidney. By light microscopy, semiquantitative scoring (0-3) was performed for arteriosclerosis, arteriolar hyalinosis (hyalin arteriolosclerosis), glomerulosclerosis, interstitial mononuclear cell infiltration, and interstitial fibrosis/tubular atrophy. Whereas vascular changes were striking in many biopsies (arteriosclerosis grades 2-3: 28/54 cases, arteriolar hyalinosis grades 2-3: 15/55 cases), glomerular and tubulointerstitial changes were mostly low grade. The morphological changes tended to be more pronounced in middle-aged and older individuals, but, in particular, vascular changes were seen also in the younger age group. Immunofluorescence microscopy revealed glomerular granular staining for IgM in 52.7% of the cases, IgA in 9.1%), IgG in 1.8%, and C3 in 12.7%. The main ultrastructural finding was glomerulosclerosis; one case with diffuse glomerular IgA showed distinct dense deposits, and one case showed similar dense deposits without IgA deposition. Arteriolar wall deposition of C3 was found in 58.2% of the cases, and IgM in 10.9%. Especially C3 occurred both with arteriolar hyalinosis and in arterioles without light microscopic alterations. The observation of significant vascular changes in baseline biopsies is relevant especially in the differential diagnosis of chronic rejection and cyclosporine nephropathy. The immunohistochemical findings strongly indicate the occurrence of immunoglobulins and complement factor C3 in both glomeruli and arterioles without clinical or morphological signs of renal disease. The possible pathophysiological significance of such deposits remains, however, uncertain.

Hematuria-loin pain syndrome: its existence as a discrete clinicopathological entity cannot be supported

OBJECTIVE

To (a) review existing literature and current concepts on Hematuria-Loin Pain Syndrome (HLPS) and (b) to describe seven cases of this syndrome.

PATIENTS AND SETTING

Seven HLPS patients seen over a period of 8 years by the pain and nephrology services of the Toronto Hospital, Toronto, Ontario, Canada.

METHODS AND RESULTS

Retrospective analysis was performed. All patients were remarkable for the variability of clinical presentation, pain characteristics, and dissociation of pain and hematuria occurrence. Routine renal investigations revealed different benign kidney pathologies in 5 of 7 patients. All patients, however, displayed variable combinations of personality factors, drug seeking behaviour, psychopathology, and presence of significant psychosocial stressors. Four cases were managed conservatively with antidepressants, anxiolytics, and supportive counseling and did very well despite persistent hematuria in two.

CONCLUSIONS

HLPS does not constitute a distinct clinicopathological entity. In a minority of cases only underlying kidney pathology is related to pain, and in many cases psychosocial stressors and underlying psychopathology may play a significant role in the reported disabling pain. A concerted medical/psychological approach is advocated.

Loin pain haematuria syndrome

Loin pain haematuria syndrome is a descriptive diagnosis of recurrent episodes of loin pain accompanied by haematuria, in which investigations do not reveal adequate pathology to account for the symptoms. The majority of patients present between 20 and 40 years, but onset may occur in older children. A significant number of patients show psychological and psychopathological features. Renal histology may show minor abnormalities, including mesangial proliferation, arteriolar and arterial hyalinosis and C3 in arterioles. Renal angiography is often normal but changes in intrarenal arterioles and cortical infarcts may be seen. Haematological abnormalities include decreased heparin-thrombin clotting time and elevated free plasma serotonin concentration. It is important that the assessment include a detailed psychiatric history, the patient's perception of pain, and the psychosocial environment. The pain may be very severe, leading to the requirement for addictive analgesics: management often becomes very difficult and frustrating to medical practitioners. Surgical intervention with capsulotomy, denervation and autotransplantation should only be considered as a last resort, as there is frequent recurrence of pain on the same or contralateral side.

Loin pain-hematuria syndrome associated with thin glomerular basement membrane disease and hemorrhage into renal tubules

Loin pain-hematuria (LPH) syndrome is a poorly understood disorder in which the patients, mainly young women, experience unexplained severe chronic unilateral or bilateral flank pain associated with gross and/or microscopic hematuria. By contrast, thin glomerular basement membrane (GBM) disease is generally thought to be a benign disorder, affecting males and females equally, in which the major manifestation is asymptomatic microscopic hematuria. Herein we describe seven patients (6 females, 1 male) in whom thin GBM appeared to be the cause of the LPH syndrome. The gross hematuria in these patients could be attributed to thin GBM disease because the renal biopsy demonstrated red cells in renal tubules (indicating glomerular hematuria) and the only glomerular abnormality present with thin GBM. In addition, the other causes of gross hematuria were excluded by appropriate testing. The flank pain in these patients might also have been the result of their thin GBM disease. This is suggested by renal biopsy findings of multiple renal tubules filled with red cells, apparently occluding the tubules. We suggest that occlusion of a relatively small fraction of renal tubules could cause renal pain if back-leak of glomerular filtrate occurred that was of sufficient magnitude to expand renal parenchymal volume and stretch the renal capsule. Preliminary observations suggest that treatment with the angiotensin converting enzyme (ACE) inhibitor enalapril importantly reduces the frequency and severity of the episodes of gross hematuria and flank pain in most patients. ACE inhibition might decrease glomerular hemorrhage in patients with think GBM by decreasing glomerular hydrostatic pressure. We conclude that (1) Thin GBM disease can be the cause of gross hematuria, apparently as a result of rupture of thin GBM. (2) Rupture of thin GBM resulting in hemorrhage into renal tubules may be the cause of the flank pain and gross hematuria in some patients with the LPH syndrome.

Loin pain hematuria syndrome: pain relief with intrathecal morphine

Loin pain hematuria syndrome (LPHS) is characterized by hematuria and incapacitating loin pain. The pain experienced with LPHS is, in general, extremely difficult to treat. Many surgical and pharmacologic therapies have been directed at LPHS pain without success. This report documents successful pain control in a patient with LPHS using long-term intrathecal morphine delivered via an implantable pump. Intrathecal narcotic therapy may provide pain relief for the chronic pain of LPHS.

Autotransplantation for intractable loin pain: report of a case with long-term followup

We report a case of autotransplantation performed 21 years ago in a patient suffering from intractable loin pain. Long-term followup, the pathogenesis of pain in regard to renal innervation and the value of autotransplantation as a form of complete sensory denervation are discussed.

Loin pain-hematuria syndrome: how effective is renal autotransplantation in its treatment?

OBJECTIVES

To evaluate our experience with renal autotransplantation in the management of loin pain-hematuria (LPH) syndrome after relatively long follow-up (30 to 35 months).

METHODS

Four patients with LPH syndrome of 3 to 18 years' duration underwent technically successful autotransplantation. All patients preoperatively had normal radiologic investigations, including renal arteriography and biopsy. All required narcotic analgesia for pain control. Patients were followed for 30 to 35 months.

RESULTS

All 4 patients were pain and narcotic free for 6 months postoperatively. At 18 months after surgery, 3 of the 4 had recurrence of the pain and at 30 months, 2 required nephrectomy. Only 1 patient of 4 had sustained pain relief at 35 months.

CONCLUSIONS

Renal autotransplantation certainly offers temporary relief from LPH syndrome, but in our experience this was not durable in the majority of our patients.

Psychiatric issues in the "loin pain and haematuria syndrome"

The Loin Pain and Haematuria Syndrome is a relatively new diagnosis applied to the problem of persistent loin pain, often with haematuria, in the absence of identifiable explanatory organic pathology. Case reports have suggested a range of salient psychopathological features associated with the complaints of pain and haematuria, although the psychological factors have been largely neglected in understanding the aetiology or in approaches to management. The roles of illness behaviour, patterns of somatisation, and psychiatric disorder associated with chronic pain syndromes, need to be addressed, as do the patterns of medical and surgical response to these patients. The use of the term "syndrome" to describe these symptoms implies a degree of uniformity in clinical features and outcome that has not yet been substantiated. New surgical techniques have been developed such as renal denervation and renal auto-transplantation to treat the pain, with limited success. A review of this condition illustrates the frequent failure of medicine to apply multi-factorial biopsychosocial models to understanding the aetiology and management of unexplained physical symptoms. It also illustrates the failure of our current nosology and understanding of somatoform disorders to achieve application outside psychiatry.

Renal autotransplantation in the loin pain-hematuria syndrome: a cautionary note

The current literature suggests that renal autotransplantation is nearly uniformly effective in controlling the severe and debilitating pain of the loin pain-hematuria syndrome (LPHS). However, we report two patients thought to have this syndrome in whom renal autotransplantation did not result in long-term control of pain. In case 1, autotransplantation resulted in immediate cessation of pain; however, the flank pain recurred 7 1/2 months later. The recurrent pain was also severe and debilitating, requiring narcotic medications for control. In case 2, autotransplantation of the left kidney resulted in chronic pain in the left pelvic area, the site of the autotransplanted kidney. In addition, the patient continued to experience chronic discomfort in the left flank and along the flank incision. One year after autotransplantation, the patient still requires multiple daily doses of narcotic medications for pain control. Our two patients represent the 13th and 14th reported patients subjected to renal autotransplantation for management of LPHS. They represent only the third and fourth reported patients with recurrence of pain after renal autotransplantation. Because studies with negative results are less likely to be reported in the literature than studies with positive results, it is possible that the literature overestimates the effectiveness of renal autotransplantation in the LPHS. To assess the true effectiveness of renal autotransplantation in LPHS, a survey of patients with LPHS who have undergone renal autotransplantation needs to be performed.

Loin pain-hematuria syndrome: role for renal autotransplantation

The loin pain-hematuria syndrome is a poorly understood constellation of symptoms consisting of persistent hematuria and intractable loin pain with negative comprehensive urological evaluation. The patients are severely debilitated by the pain and are usually dependent on narcotics. Various medical and surgical treatments have been tried unsuccessfully, ultimately leading to nephrectomy in many instances. The symptoms may subsequently occur contralaterally. Renal autotransplantation as a form of nephron-sparing denervation therapy for relief of pain was performed on 12 kidneys in 10 patients (2 bilaterally). Excluding 3 patients with followup of less than 1 year (all 3 are pain-free), 8 of the 9 autotransplantations have resulted in dramatic relief of pain, curtailment of narcotic use and return of the patient to normal daily function. Median followup was 43 months (range 15 to 53 months). The remaining patient had pain in the graft area necessitating transplant nephrectomy 4 months later. For patients severely affected by pain and narcotic dependence with this syndrome, renal autotransplantation may provide a nephron-sparing surgical solution.

Afferent arteriolar C3 disease--a distinct pathological entity

Afferent arteriolar C3 deposition was the sole histological abnormality in 79 and the major histological abnormality in an additional 39 of 959 renal biopsies performed over a 10-year period. Of these 79 patients, hematuria was the presenting symptom in 90%, with coincident loin pain in 49%. Urine microscopy of asymptomatic first-degree relatives revealed hematuria in 44% of children and siblings and 54% of parents, suggesting autosomal dominant inheritance. Arteriolar C3 deposition was confirmed by biopsy in four asymptomatic relatives with hematuria. Generalized thinning of glomerular basement membrane (less than 200 nm) was observed in five patients and focal thinning was observed in six patients with coincident afferent arteriolar C3 deposition. Seven other patients were identified as having generalized thinning of glomerular basement membrane in the absence of afferent arteriolar C3 deposition. Renal function was stable and similar in all groups studied over 37.9 +/- 23.7 months. No difference in clinical presentation or urinary abnormalities was evident between the groups. No arteriolar C3 deposition was evident in eight autopsy specimens with no known renal disease. It was concluded that afferent arteriolar C3 deposition is a marker of a distinct hereditary pathological entity, with differentiation from thin basement membrane disease not possible on clinical grounds. The medium- and long-term prognoses with respect to renal function are excellent.

Platelet activation and prostacyclin supporting capacity in the loin pain hematuria syndrome

The loin pain hematuria syndrome has been characterized as a constellation of severe recurrent flank pain and hematuria, occurring predominantly in young women. We studied a 17-year-old woman who had recurrent right flank pain, gross hematuria, and fever, without evidence of urinary tract infection. Her physical exam was remarkable for right costovertebral angle tenderness and a normal BP. Her urinalysis showed blood and protein but her creatinine clearance and 24-hour urinary calcium excretion were normal. A kidney biopsy was remarkable for arteriolar subintimal fibrous thickening and fibrin deposition, but no glomerulonephritis. Her peripheral hemostasis evaluation was normal except for circulating platelet aggregates and elevated fibrinopeptide A levels. On two occasions, her serum was unable to normally support prostacyclin (PGI2) production by cultured human umbilical endothelial cells, as measured by radioimmunoassay (RIA) of its stable metabolite 6-keto-PGF alpha. Blood samples from the right renal vein and inferior vena cava revealed a selective elevation of fibrinopeptide A in the right renal venous effluent. The presence of circulating platelet aggregates and elevated levels of fibrinopeptide A (a cleavage product of fibrin) suggests that platelet activation and fibrin deposition may play a role in the pathogenesis of this disorder. The inability of her serum to normally support the production of the potent antiplatelet and antithrombotic substance, PGI2, could represent a primary renovascular endothelial cell defect.

Analgesics and warfarin. A case that brings up questions and cautions

This case report describes prolongation of a patient's prothrombin time and partial thromboplastin time possibly due to coadministration of warfarin and an overdose of an acetaminophen-propoxyphene combination analgesic. Patients receive warfarin for many indications, and concomitant use of an analgesic agent is commonly required. These patients should be closely observed if a combination acetaminophen-propoxyphene product is prescribed. Finally, patients receiving warfarin should be warned about the risks of use (and overdose) of unprescribed medications.

The pathogenesis of hyaline arteriolosclerosis

Although hyaline arteriolosclerosis is very common and has been of interest to pathologists for well over 100 years, its pathogenesis has never been determined. This study demonstrates that iC3b bound via an ester linkage to hydroxyl groups on the repeating disaccharide units of hyaluronic acid is a major component of arteriolar hyaline. The deposition of iC3b within the walls of arterioles appears to be due to slow spontaneous activation of the alternative complement pathway and random binding of metastable C3b to proximate hyaluronic acid within the arteriolar wall. Since hyaluronic acid does not activate the alternative complement pathway, bound C3b is rapidly inactivated by factors I and H to iC3b, which, along with factor H, remains bound to hyaluronic acid. The hyaline in some hyalinized arterioles also contains IgM and early and late classical complement pathway components. Indirect evidence suggests that the IgM represents immunoconglutinin, an autoantibody to neoantigens on iC3b and that their interaction results in activation of the classical complement pathway. The gradual accumulation of iC3b, factor H, and, at times, IgM and classical complement pathway components within the walls of arterioles is considered to be a physiologic consequence of aging and probably cannot be prevented, because interruption of the initial binding of metastable C3b to hyaluronic acid would require abrogation of the critically important functions of the alternative complement pathway.

Renal autotransplantation for severe loin-pain/haematuria syndrome

Most forms of therapy for the loin-pain/haematuria syndrome are unsuccessful, though nerve-block procedures and renal denervation sometimes provide temporary relief. Three young patients, with pain so severe that they were dependent on narcotics, were treated for this syndrome. All three had been repeatedly admitted to hospital. Loin pain was unilateral in two patients and predominantly so in the third. Renal function, excretion urography, and angiography were normal, but renal biopsy specimens showed deposition of the third component of complement in the renal arterioles. All were treated with renal autotransplantation; the kidney causing pain (or the one causing the most pain) was completely excised and reimplanted in the iliac fossa. Two patients had complete relief of pain and the third almost complete relief, despite recurrence of haematuria in all three. It is too early to determine whether this major procedure is justified in the treatment of the loin-pain/haematuria syndrome, but the early results are encouraging.

Immunoelectron microscopy of IgA nephropathy

The distribution of IgA, IgG, IgM, C3, and albumin in kidney biopsy specimens from 11 children and adults with recurrent gross and microscopic hematuria and IgA nephropathy and 7 control specimens were evaluated by the direct peroxidase-labeled antibody method and electron microscopy. Granular masses of reaction product (RP), representing IgA, IgG, IgM, and C3, were observed within the mesangial matrix of glomeruli from all patients with IgA nephropathy. Occasional smaller masses of IgA-RP and C3-RP were noted along the peripheral glomerular capillary loops, the tubular basement membranes, and within the interstitial matrix of some patients. Large amounts of IgA-RP and C3-RP were present within the walls of small renal arterioles of several patients. These observations support the concept that immune-complex deposits are involved in the pathogenesis of IgA nephropathy and suggest that vascular deposits may have a more important role in the progression of the disease in some patients.

The natural history and management of the loin pain/haematuria syndrome

This is a rare, but potentially very troublesome disorder. We have been able to carry out detailed radiological, histological and biochemical investigations on 51 patients and the results of these investigations are presented. Considerable evidence of abnormal platelet activity has been found. The histological evidence has come from both biopsy and nephrectomy specimens and has shown aggressive atherosis leading to microembolic lesions and in some cases showing microaneurysm formation. In some instances this has led to areas of infarction both small and large. Most of the cases studied have been fully followed up and it has been found that despite the histological changes, the blood pressure remains normal and no demonstrable deterioration in renal function occurs. Attempts at treatment are described and discussed.

The loin pain-haematuria syndrome in males

Three young male patients with severe loin pain and intermittent haematuria are presented as examples of the loin pain—haematuria syndrome which has previously been described only in young women. The incapacitating severity of the loin pain and the lack of specific diagnostic tests are emphasised.

The loin-pain/haematuria syndrome

Nine patients with the loin-pain/haematuria syndrome are described. The previously reported clinical features of severe recurrent loin pain and tenderness in young women, the relationship of symptoms to use of oral contraceptives, and the demonstration of intrarenal vascular abnormalities by angiography are confirmed. Histology revealed minor non-specific abnormalities, and electron microscopy showed fibrin in the afferent arteriole and in glomerular capillaries of one patient only. No diagnostic changes were found on renography. In all patients except one the heparin-thrombin clotting-time was abnormal, suggesting increased platelet activity or release and providing further evidence of a vascular disorder.