N21 refers to Calculus of lower urinary tract, describing various forms of urinary tract stone disease that cause obstruction, severe pain (renal colic), and potential kidney damage if not promptly treated.

Symptoms

Severe flank or abdominal pain – Hallmark of renal colic (N20, N23)
Hematuria (blood in urine) – Due to stone irritation of urinary tract walls
Frequent or painful urination – Especially in lower urinary tract stones (N21)
Nausea and vomiting – Common with acute obstruction
Urinary urgency – Particularly when bladder stones are involved

Diagnosis

Diagnosis of Calculus of lower urinary tract relies on clinical presentation, urinalysis (for blood or crystals), non-contrast CT scans of the abdomen/pelvis (gold standard), renal ultrasound, and plain abdominal X-rays in certain cases.

ICD10 Code Usage

ICD10 code N21 is used by urologists, nephrologists, emergency medicine physicians, and internists to document urinary stone disease, guide treatment such as lithotripsy, ureteroscopy, or surgery, and monitor recurrence risk.

Related Codes

FAQs

Q1: What is ICD10 code N21?
A: It refers to Calculus of lower urinary tract, covering kidney, ureter, bladder, and unspecified urinary stones presenting with pain, hematuria, or urinary obstruction.

Q2: What is the difference between N20 and N21?
A: N20 refers to stones in the kidney or ureter, while N21 refers to stones located in the bladder or urethra (lower urinary tract).

Q3: What is N23 (unspecified renal colic)?
A: Used when a patient presents with classical renal colic symptoms but the specific stone location or cause is not yet confirmed through imaging.

Q4: What causes urinary tract calculi?
A: Causes include dehydration, dietary factors (high oxalate or protein intake), infections, metabolic disorders, and family history.

Q5: How are urinary stones treated?
A: Small stones often pass spontaneously; larger stones may require medications, shock wave lithotripsy, ureteroscopy, or surgical removal depending on size and location.

Conclusion

ICD10 code N21 ensures accurate diagnosis, documentation, and management of Calculus of lower urinary tract, enabling effective treatment to relieve symptoms, prevent complications, and reduce future stone formation risks.