What are the components of a basic metabolic panel (BMP) for patients with kidney stones, particularly those with a family history of kidney stones or underlying medical conditions such as gout or inflammatory bowel disease?

Basic Metabolic Panel Components for Kidney Stone Evaluation

The basic metabolic panel (BMP) for kidney stone patients should include serum electrolytes, calcium, creatinine, and uric acid as the foundational screening evaluation. 1

Core BMP Components

The screening serum chemistries must include:

• Electrolytes (sodium, potassium, chloride, bicarbonate/CO2) to identify underlying metabolic abnormalities and acid-base disturbances 1, 2
• Serum calcium to detect hypercalcemia that may suggest primary hyperparathyroidism, particularly when elevated or high-normal 1
• Creatinine and BUN to assess renal function, as uric acid stone formers typically show the highest creatinine levels 2, 3
• Uric acid to identify hyperuricemia associated with uric acid stone formation 1

Additional Screening Components Beyond Standard BMP

While not technically part of a "basic" metabolic panel, the initial evaluation must also include:

• Urinalysis with dipstick and microscopic examination to assess urine pH, detect infection indicators, and identify pathognomonic crystals 1, 2
• Urine culture if urinalysis suggests infection or in patients with recurrent UTIs 1, 2
• Serum intact parathyroid hormone (PTH) when serum calcium is high or high-normal to rule out primary hyperparathyroidism 1, 4

High-Risk Patients Requiring Expanded Evaluation

For patients with family history of kidney stones, gout, inflammatory bowel disease, or other high-risk features, the evaluation extends beyond the BMP:

• Comprehensive 24-hour urine metabolic testing is mandatory for all recurrent stone formers and high-risk first-time formers, analyzing volume, pH, calcium, oxalate, uric acid, citrate, sodium, potassium, and creatinine 1, 5, 4
• Urinary cystine measurement for patients with known or suspected cystine stones or family history of cystinuria 1, 4
• Stone analysis at least once when stone material is available, as composition directly guides preventive therapy 1, 5, 4

Clinical Context and Limitations

The BMP alone has only 59% accuracy in predicting stone type, so it cannot replace stone analysis or 24-hour urine testing 3. However, specific patterns emerge: uric acid stone formers demonstrate the highest serum glucose, BUN, and creatinine levels, while calcium oxalate formers show the highest serum sodium 3. Notably, mean serum calcium levels do not significantly differ across stone types, limiting its discriminatory value 3.

Practical Algorithm

1. All kidney stone patients: Obtain BMP (electrolytes, calcium, creatinine, uric acid) plus urinalysis 1, 2
2. If serum calcium elevated/high-normal: Add serum PTH 1, 4
3. If urinalysis suggests infection: Obtain urine culture 1
4. If recurrent stones, family history, gout, IBD, or other high-risk features: Proceed to 24-hour urine metabolic testing 1, 5, 4
5. When stone available: Always obtain stone analysis 1, 4

Research demonstrates that 92.3% of first-time stone formers have detectable metabolic abnormalities, with 60% having two or more abnormalities, justifying comprehensive evaluation even in first-time formers with risk factors 6.