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Cystine (Cys₂) Unit Converter
Cystine (Cys₂) is the stable, oxidized dimer of the amino acid Cysteine, formed when two cysteine molecules link via a disulfide bond. Cystine is the primary storage and transport form for cysteine. The molecule itself is characterized by poor solubility, which is the direct cause of its associated pathology.
In clinical practice, cystine measurement is crucial for diagnosing Cystinuria, an inherited defect in renal tubular transport where cystine is inefficiently reabsorbed. High concentrations of cystine in the urine lead to the formation of characteristic hexagonal crystals and recurrent kidney stones (calculi). Cystine measurements are often performed in conjunction with Cysteine to assess the status of the body’s entire sulfur-containing amino acid pool.[Image of amino acid transport defects in renal tubule]
SI Units
RecommendedMicromoles per liter (Standard International).
Conventional Units
Clinical Context
Cystine levels are normally extremely low in the urine due to efficient reabsorption. Urine concentrations exceeding 250-300 mg/day confirm the diagnosis of Cystinuria.
While plasma levels are rarely used for diagnosis, urinary cystine monitoring is essential for guiding therapy, which typically involves high fluid intake, urine alkalinization (potassium citrate), and potentially chelation therapy. The conversion factor is based on MW $240.30 \text{ g/mol}$: 1 mg/dL $\approx$ 41.6 µmol/L.
Clinical References
How to Use This Calculator
Follow these steps to get accurate clinical conversions instantly.
Enter Values
Input your laboratory results into the corresponding unit field (e.g., mg/dL). You can use either dot or comma decimals.
Automatic Conversion
The calculator works in real-time. As you type in one field, all other units (like µmol/L) are instantly updated.
Verify Units
Check the SI Units section. µmol/L is the standard unit for amino acid analysis.
Reset
Use the Clear button to reset all fields before starting a new calculation.
Frequently Asked Questions & Tips
1 mg/dL = 41.6 µmol/L. This is based on the molecular weight of Cystine (240.30 g/mol).
No, but the repeated formation of kidney stones (calculi) can lead to obstruction and subsequent damage if not properly managed.