Table 4.
Blood Phe metabolism model parameters.
| Parameter/state variable | Description | Value | Initial value | Units |
|---|---|---|---|---|
| Phe | Plasma Phe concentration | - | 1.18 | mmol/L |
| Gut | Gut Phe content | - | 0 | mg |
| t | Time | - | - | hr |
| Ka,gut | Absorption rate from the gut to plasma | 0.25 | - | 1/hr |
| Vnpd | Rate of net protein breakdown | 0.012 | - | (mmol/L)/hr |
| VPAH | Rate of Phe breakdown by PAH | - | - | (mmol/L)/hr |
| Vtrans | Rate of Phe breakdown by transaminase | - | - | (mmol/L)/hr |
| Vrenal | Rate of renal Phe elimination | - | - | (mmol/L)/hr |
| Vmax,PAH | Maximum rate of Phe breakdown by PAH in a healthy subject | 0.9 | - | (mmol/L)/hr |
| FPAH | Fraction of healthy PAH activity | 0.0–1.0 | - | Unitless |
| Km,PAH | Michaelis–Menten constant for Phe with PAH | 0.51 | - | mmol/L |
| Ka,PAH | Phe activation constant for PAH | 0.54 | - | mmol/L |
| Vmax,trans | Maximum rate of Phe breakdown by transaminase | 0.063 | - | (mmol/L)/hr |
| Km,trans | Michaelis–Menten constant for Phe with transaminase | 1.37 | - | mmol/L |
| CLrenal | Renal clearance of Phe per body weight | 5.696 × 10−4 | - | (L/kg)/hr |
| FGut,Plasma | Unit conversion adjustment from Gut to Plasma concentrations | - | - | (mmol/L)/mg |
| MWPhe | Molecular weight of Phe | 165.19 | - | g/mol |
| Vd | Volume distribution of Phe | 0.5 | - | L/kg |
| W | Body weight | 70 | - | kg |