12. A 22-year-old G2P1, at gestational amenorrhea of 35 weeks has presented to the labour ward complaining of headache, abdominal pain, nausea, vomiting and widespread itching with no rash. On examination there is mild jaundice and bilateral pedal edema. Her BP is 150/95 mm Hg, urine albumin 1+ . FBC, LFT , U&E, clotting screen and serum urate awaited. What is the single most important test that could help to distinguish AFLP from HELLP and severe pre.eclampsia?