Symptoms of acute poststreptococcal glomerulonephritis

The symptoms of acute poststreptococcal glomerulonephritis caused by hemolytic streptococcus group A are well known. The development of nephritis is preceded by a latent period, which after pharyngitis is 1-2 weeks, and after a skin infection is usually 3-6 weeks. During the latent period, microhematuria is detected in some patients, preceding the full clinical picture of nephritis.

In some patients, the symptoms of acute poststreptococcal glomerulonephritis consist of the presence of microhematuria only, while in others, macrohematuria, proteinuria, sometimes reaching nephrotic levels (>3.5 g/day/1.73 m2), arterial hypertension, and edema develop ^. In rare cases, the clinical course becomes "rapidly progressive", with rapidly increasing uremia, which is usually combined with the development of widespread extracapillary proliferation in the glomeruli and the formation of a large number of "crescents" (extracapillary nephritis). However, more often, the symptoms of acute poststreptococcal glomerulonephritis are virtually absent. During epidemics, the number of patients with the subclinical form is 1.5 times higher than the number of patients with a full-blown clinical picture. In a study of children with streptococcal upper respiratory tract infection, there were 19 subclinical cases for every case of nephritis with clinical manifestations. In prospective studies in families, the ratio of subclinical to clinical cases ranged from 4.0 to 5.3.

Acute nephritic syndrome as a manifestation of the acute period of scarlet fever was first described during the epidemic in the 18th century. Acute nephritic syndrome remains the most characteristic manifestation of acute diffuse proliferative poststreptococcal glomerulonephritis and is usually called acute glomerulonephritis. 40% of patients have a detailed clinical picture of acute nephritic syndrome - edema, hematuria, hypertension, oliguria, and 96% of patients have at least two of these symptoms. A typical picture of a patient with acute diffuse proliferative poststreptococcal glomerulonephritis is a boy from 2 to 14 years old, who suddenly develops edema of the eyelids and face, urine becomes dark with a decrease in its amount, blood pressure increases. In a typical case, the volume of urine increases after 4-7 days, followed by a rapid disappearance of edema and normalization of blood pressure.

• Hematuria is a mandatory sign, which may be the only manifestation of nephritis; only in exceptional cases can the diagnosis of acute glomerulonephritis be made with a normal urine sediment. Microhematuria is detected in 2/3 of patients, in the rest the urine is dark brown. Macrohematuria usually disappears after an increase in diuresis, but microhematuria may persist for many months after the acute period.
• Edema is the main complaint of most patients. In adolescents, edema is usually limited to the face and ankles, while in younger children it is more generalized. The cause of edema in acute glomerulonephritis is a decrease in glomerular filtration - a functional manifestation of damage to the renal glomeruli: the inflammatory reaction in the glomeruli leads to a decrease in CF, reducing the filtration surface of the capillaries and causing shunting of blood between the capillaries. In this case, renal blood flow is normal or even increased. Another cause of edema is severe sodium retention, which is also observed in patients with moderately reduced CF, while diuresis can spontaneously increase even before CF is restored.
• Hypertension develops in more than 80% of patients, but only half of them require antihypertensive drugs; rarely, the course of acute glomerulonephritis is complicated by the development of hypertensive encephalopathy. If symptoms of CNS involvement develop - drowsiness or seizures - it is necessary to keep in mind the possibility of systemic lupus erythematosus or hemolytic uremic syndrome. The cause of arterial hypertension in acute glomerulonephritis is an increase in the volume of circulating blood associated with fluid retention, combined with an increase in cardiac output and peripheral vascular resistance. The course of acute nephritic syndrome can be complicated by the development of congestive heart failure as a result of fluid retention and severe arterial hypertension.
• Proteinuria is a very important sign of glomerular disease, the result of damage to the capillary wall of the glomerulus. Proteinuria of 3 g/day or more, isolated or combined with other signs of nephrotic syndrome, is observed only in 4% of children with the clinical picture of acute poststreptococcal glomerulonephritis, in contrast to the high frequency of "massive" proteinuria in adults with this and other diseases with the morphology of endocapillary proliferative glomerulonephritis (systemic lupus erythematosus, "shunt" nephritis, nephritis in visceral abscesses).

Non-specific symptoms of acute post-streptococcal glomerulonephritis - general malaise, weakness, nausea, sometimes with vomiting, often complement the clinical signs of acute glomerulonephritis.

About 5-10% of patients experience dull pain in the lower back, which is explained by stretching of the renal capsule as a result of parenchymal edema. The course of acute glomerulonephritis in children and adults (especially elderly) patients differs significantly. In adults, dyspnea, congestion in the lungs, oliguria, massive proteinuria, azotemia and death in the acute period of the disease are observed much more often. A poor prognosis may be associated with concomitant diabetes, cardiovascular and liver diseases or with the severity of the kidney disease itself.

Symptoms of acute diffuse proliferative poststreptococcal glomerulonephritis

Symptoms	Frequency, %
Edema	85
Macrohematuria	30
Lower back pain	5
Oliguria (transient)	50
Hypertension	60-80
Nephrotic syndrome	5

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