Female urine smells like ammonia

Normal people's urine generally has no obvious irritating smell, but some patients will find that their urine emits a significant odor when they urinate. This situation requires extreme attention. Let’s discuss below, why does women’s urine smell like sodium hydroxide?

(I) Causes of the disease

More than 95% of urinary tract infections are caused by a single pathogen. Among them, 90% of outpatients and about 50% of outpatients were infected with Escherichia coli. There are more than 140 species of this bacteria in the clinical diagnosis of blood cells. The urinary infection-causing Escherichia coli is the same type of Escherichia coli extracted from the patient's feces, and is common in asymptomatic bacteriuria or urinary infection without complications; Proteus, Clostridium difficile, Klebsiella pneumoniae, Pseudomonas aeruginosa, and fecal Streptococcus are common in patients with reinfection, indwelling catheters, and urinary infection with complications; Candida albicans and Cryptococcus neoformans infections are common in patients with diabetes and those using hormone drugs and immunosuppressants and after kidney transplantation; Staphylococcus aureus is common in bacteremia and sepsis caused by skin trauma and drug addicts; although viral infections and chlamydia infections are rare, they have been gradually increasing in recent years. Various bacterial infections are common in indwelling catheters, neurogenic bladders, stones, congenital malformations, and vaginal, gastrointestinal, and urethral fistulas.

The types of bacteria that cause urinary tract infections are shown in Table 1.

2. Pathogenesis

Urinary tract infection is caused by the invasion of pathogens, and its pathogenesis is related to pathogen infection. The ways and methods of pathogen invasion and infection can be roughly divided into the following categories.

1. In about 95% of urinary tract infections, the bacteria spread from the urethra through the bladder and urethra to the kidneys. Under normal circumstances, there are a small number of bacteria 1 to 2 cm above the urethral opening. Only when the body's resistance is reduced or the urethral mucosa is damaged can the bacteria invade and multiply. The cleansing in urine, the IgA, lysozyme, citric acid in urine, the consistency of the mucosa, and the anti-adhesion factor (Muein) metabolized by bladder transitional epithelial cells can all inhibit the invasion of pathogens. In recent years, transmission electron microscopy has confirmed that there are many P pili on the surface of Escherichia coli, which can specifically identify and bind to the corresponding protein kinases on the surface of urethral squamous epithelial cells, thereby making the bacteria tightly adhere to the urethral squamous epithelial cells to prevent being washed away by urine. Escherichia coli has somatic (O) antigen, flagellar (H) antigen, and capsule (K) antigen. The K antigen of the nucleotide can inhibit the bactericidal specificity of tissue cells, and the pathogenicity of the two is directly related. Proteus lacks P pili and K antigens, and does not easily adhere to the transitional epithelial cells of the bladder, but can adhere to the squamous epithelial cells of the reproductive organs. Indwelling catheters, urethral stones, trauma, tumors, prostatic hyperplasia, congenital urethral malformations (including intramural urethra, bladder urethral reflux caused by dysplasia), neurogenic bladder, etc. are all risk sources of increased infection.

2. Hematogenous infection Hematogenous infection accounts for less than 3% of urinary tract infections. The blood volume of the kidney accounts for 20% to 25% of the cardiac output. In sepsis and bacteremia, the bacteria in the circulating blood can easily reach the renal cortex. Diabetes, polycystic kidney disease, transplanted kidney, urinary tract obstruction, renal vascular obstruction, the use of analgesics or sulfonamides increase the vulnerability of renal tissue. Common pathogens include Staphylococcus aureus, Salmonella, Pseudomonas and Candida albicans. Direct infection is rare, and infection through the lymph node tract has not been confirmed.

3. Infectious factors

(1) Urinary tract obstruction: Urinary tract obstruction caused by various reasons, such as kidney and ureteral stones, urethral stenosis, urinary system tumors, prostate hyperplasia, etc. can all cause urine retention, making it easy for bacteria to multiply and cause infection. The disease can be caused by compression of the urethra by the uterus during pregnancy, kidney ptosis or hydronephrosis, which can hinder urine metabolism and lead to this disease.

(2) Malformations or abnormal functions of the urinary and reproductive systems: such as renal dysplasia, polycystic kidney, sponge kidney, horseshoe kidney, double renal pelvis or double urethra malformation and extremely large urethra, which can easily reduce the resistance of some tissues to pathogens. Bladder reflux causes urine to flow back from the bladder into the renal pelvis, thus increasing the chance of disease. Neurogenic bladder urination disorder causes urine retention and bacterial infection.

(3) Inspection of urethral catheterization and equipment: Catheterization, cystoscopy, and urinary system surgery can all cause partial mucosal damage, bringing pathogens from the anterior urethra to the bladder or upper urethra and causing infection. According to surveys, the incidence of persistent bacteriuria after a catheterization is 1% to 2%; if the catheter is left in place for more than 4 days, the incidence of persistent bacteriuria is more than 90%, and there is a high risk of serious pyelonephritis and Gram-negative sepsis.

(4) Anatomical and physiological characteristics of the female urinary tract: The female urethral opening is only 3 to 5 cm long, straight and wide, and the urethral sphincter is weak. Bacteria can easily rise along the urethral opening to the bladder. In addition, the urethral opening is close to the anus, which provides conditions for bacteria to invade the urethral opening. Local irritation around the urethral opening, susceptibility of the vulva to fungal infection during menstruation, gynecological diseases such as vaginitis and cervicitis, and estrogen changes during pregnancy, childbirth and sexual intercourse can all cause changes in the vaginal and urethral mucosa and facilitate the invasion of pathogens. Therefore, the incidence of urinary tract infection in adult women is 8 to 10 times higher than that in men.

(5) Weakened body resistance: Systemic diseases such as diabetes, hypertension, chronic kidney disease, intestinal dysfunction, and long-term use of adrenal growth hormone reduce the body's immunity and significantly increase the incidence of urinary tract infection.