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Human immunodeficiency virus–associated kidney disorders

1. How do you begin the evaluation of kidney disease in the setting of human immunodeficiency virus (HIV) infection? The differential diagnosis of kidney disease in the setting of HIV infection covers a wide spectrum of kidney disorders including acid-base and electrolyte abnormalities, glomerular disease, acute kidney injury (AKI), and chronic kidney disease (CKD). There is no difference in the initial basic approach in the evaluation…

Viral hepatitis-associated glomerulonephritis

1. What types of viral hepatitis are associated with glomerulonephritis? Chronic carriers of hepatitis B (HBV; 400 million people worldwide) or hepatitis C (HCV; 170 million people worldwide) are at increased risk of developing a variety of glomerular diseases linked directly to active viral replication. By definition, a carrier state for these viruses would be characterized by a positive quantitative polymerase chain reaction (PCR) assay. For…

Streptococcal- and staphylococcal-related glomerulonephritis

1. Wasn’t this category previously called postinfectious glomerulonephritis (PIGN)? There has been considerable effort to reclassify glomerular diseases that occur as a result of an infection. PIGN describes a unique clinical and pathogenic sequence of events that lead to an immune complex–mediated glomerulonephritis after resolution of an acute infection. Specifically, the acute glomerulonephritis develops after (post) a latent period of variable duration from the time the…

Vasculitides

1. Which of the vasculitides are most often associated with glomerular disease? The small-vessel vasculitides are most often associated with glomerular disease ( Fig. 33.1 ). Immunoglobulin (Ig)A vasculitis (Henoch-Schölein-purpura) and cryoglobulinemic vasculitis are associated with immune complex deposition. Pauci-immune glomerulonephritis demonstrates little to no immune deposits and is seen in the antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides, including granulomatosis with polyangiitis (GPA, formerly Wegener granulomatosis), microscopic…

Lupus nephritis

1. How common is systemic lupus erythematosus (SLE), and how often is lupus nephritis present in patients with this disease? The prevalence of SLE in the United States is around 40/100,000 (0.04%); it has a peak age of onset of 20 to 40 years and is more common in women and certain ethnic groups (especially African Americans). Kidney involvement occurs in 40% of patients with SLE,…

Diabetic kidney disease

1. Define the terms diabetic nephropathy (DN) and diabetic kidney disease (DKD). The terms DN and DKD are used interchangeably to describe a set of characteristic clinical and pathologic findings. The main clinical findings of DKD are the presence of albuminuria, progressive chronic kidney disease (CKD), and less commonly microscopic hematuria. Diabetes is the most common cause of the nephrotic syndrome. Proteinuria is first detected by…

Membranoproliferative glomerulonephritis

1. What is membranoproliferative glomerulonephritis (MPGN)? (MPGN) is a rare form of glomerular disease that occurs in both children and adults. It is characterized by a unique histopathologic feature, namely splitting of the glomerular basement membrane (GBM) with interposition of mesangial cells and extracellular matrix material. It is associated with variable degrees of endothelial and mesangial hypercellularity. Together with postinfectious glomerulonephritis, systemic lupus erythematosus (SLE), and…

Immunoglobulin a nephropathy and Henoch–Schönlein disease

1. What is immunoglobulin a nephropathy (IGAN)? IgAN is a glomerular disease characterized by the deposition of type A immunoglobulin in the mesangial areas of the glomerulus. This leads to inflammation and damage to the glomerulus and the surrounding structures. Originally known as Berger disease, IgAN is the most common biopsy-proven primary glomerular disease. 2. What are the typical biopsy findings in IGAN? On light microscopy…

Membranous nephropathy

1. What is membranous nephropathy (MN)? MN is a common immune-mediated glomerular disease that remains the leading cause of nephrotic syndrome in white adults. It is a histologic diagnosis based on the presence of immunoglobulins (Ig; usually IgG and C3) deposition along the capillary walls on immunofluorescence microscopy and subepithelial deposits along the glomerular basement membrane (GBM) on electron microscopy (EM). MN can be either a…

Focal segmental glomerulosclerosis

1. What is focal segmental glomerulosclerosis? Focal segmental glomerulosclerosis (FSGS) is a class of glomerular diseases defined by focal and segmental patterns of scar in the kidney glomeruli. This disease spectrum includes primary, genetic, and secondary diseases. Primary FSGS is diagnosed in patients without a known cause. There are a number of genetic mutations that disrupt the structure and function of the glomerular podocyte and slit…

Minimal change disease

1. What are the diagnostic criteria for nephrotic syndrome? Nephrotic syndrome is a syndrome that results from severe proteinuria. Heavy glomerular protein losses (≥3.5 g in an adult or >40 mg/m 2 per hour in a child) lead to the other three criteria for nephrotic syndrome: hypoalbuminemia, hyperlipidemia, and edema. From a practical standpoint, measuring a urine total protein-to-creatinine ratio is preferable to collecting a 24-hour…

Drug dosing in patients with chronic kidney disease

1. How can chronic kidney disease (CKD) alter the pharmacokinetic behavior of most drugs? CKD directly and indirectly affects the pharmacokinetic properties of most drugs. Alterations of drug pharmacokinetics in patients with kidney failure are based on changes in absorption, distribution, metabolism, and elimination. 2. How can changes in absorption resulting from CKD alter the pharmacokinetic behavior of drugs? Alkaline saliva. As CKD progresses, saliva becomes…

Clinical management of chronic kidney disease

1. How do you recognize progressive kidney failure? Progressive kidney failure is recognized by an increasing serum creatinine over time. However, some patients may have a normal creatinine early in the course of their chronic kidney disease (CKD). Individuals with an abnormal urinary sediment (e.g., proteinuria or hematuria) or abnormal pathology on a kidney biopsy are at risk for progressive kidney failure. Because serum creatinine is…

Nutrition

1. What is malnutrition? To define malnutrition, an expert panel of the International Society of Renal Nutrition and Metabolism (ISRNM) has recommended the use of the term “protein-energy wasting” (PEW) to encompass states of undernutrition that could result from a complex interplay of decreased nutrient intake and/or increased catabolism. 2. How is nutritional status examined, and how is malnutrition diagnosed in patients with chronic kidney disease…

Dyslipidemia

1. What is the typical lipid profile in patients with chronic kidney disease (CKD)? Dyslipidemias are common in patients with CKD, those on dialysis (both hemodialysis and peritoneal dialysis), and those who have undergone kidney transplantation. Dyslipidemia is also prevalent in over 60% of people who have received cardiac or liver transplantation, and this may be partially due to the long-term use of calcineurin inhibitors and/or…

Cardiovascular disease

1. What is the relationship between the decrease in the glomerular filtration rate and cardiovascular disease? Patients with chronic kidney disease (CKD) have a substantial increase in risk for death from cardiovascular disease. Even small decreases in kidney function, as measured by the estimated glomerular filtration rate (eGFR), are associated with this higher risk, and it increases progressively as kidney function declines. Patients with CKD are…

Bone and mineral metabolism

1. What is chronic kidney disease–mineral and bone disorder (CKD-MBD)? CKD-MBD is a systemic disorder of mineral and bone metabolism resulting from CKD that may be manifested by either one or a combination of the following: Laboratory abnormalities associated with disturbed mineral metabolism, including abnormalities of: Calcium Phosphorus, Parathyroid hormone (PTH) Vitamin D metabolites Bone disease defined as renal osteodystrophy (ROD) including abnormalities in: Bone turnover…

Anemia in chronic kidney disease

1. What causes anemia in patients with kidney disease? The anemia of chronic kidney disease (CKD) is primarily caused by deficiency of erythropoietin (EPO). The kidneys are the major source of EPO, and as kidney function declines, production of EPO declines proportionately. Several other factors decrease red blood cell (RBC) life span from the normal 120 days to approximately 70–80 days in patients with CKD. These…

Epidemiology, etiology, pathophysiology, and staging of chronic kidney disease

1. What is the definition of chronic kidney disease (CKD)? CKD is defined as the presence of kidney damage or decreased kidney function (defined as estimated glomerular filtration rate [eGFR] <60 mL/min per 1.73 m 2 ) for 3 or more months, irrespective of the cause. The persistence for at least 3 months is necessary to distinguish CKD from acute kidney injury (AKI). Markers of kidney…

Nephrolithiasis

1. How common are kidney stones? In industrialized countries, approximately 12% of men and 7% of women will form at least one kidney stone in their life, and the prevalence of nephrolithiasis is increasing. Historically men were much more likely to form kidney stones than women, but recent data show the prevalence in women is approaching that of men. After presenting with their initial stone, about…