A 27-year-old female presented to the Gout Clinic of Peking Union Medical College Hospital with recurrent arthritis and infertility. Fourteen years before presentation, she noticed protrusion of her right ankle but did not undergo evaluation at a hospital. Eight years before presentation, at age 19, she experienced acute pain and swelling of her right ankle. The pain resolved spontaneously but recurred 6 to 7 times/year, involving the bilateral metatarsophalangeal (MTP) joints, bilateral ankles, and right knee. Her serum urate level (SUA) was elevated to 789 μmol/L. A diagnosis of gout was made, and she was prescribed NSAIDs for pain relief and allopurinol and benzbromarone to lower her urate level. However, she discontinued allopurinol and benzbromarone on her own as these medications triggered acute flares. Five years before presentation, she noticed multiple nodules in her MTP joints, ankles, and fingers. The nodules on her feet interfered with normal walking. She also complained of the inability to conceive after 3 years of attempts. Her age at menarche was 14 years, and her cycles were irregular. She was reported to prefer snacks and fatty food during her childhood. Her father had hypertension. Her grandfather had an SUA level greater than 400 μmol/L but without gout. On physical examination, the patient was generally healthy, with a height of 168 cm and a weight of 55 kg. Her blood pressure was 120/80 mmHg. Cardiac and pulmonary examinations were normal. On abdominal palpation, the liver was enlarged with a normal soft texture. A joint examination revealed multiple nodules on the bilateral MTP1 joints, ankles, and fingers.
A serological examination after overnight fasting revealed a SUA level of 548 μmol/L, serum creatinine (Cr) level of 49 μmol/L, fasting glucose level of 3.6 mmol/L, total triglyceride level of 6.22 mmol/L, and total cholesterol level of 6.60 mmol/L. Her resting lactate level was 7.4 mmol/L. Her 24-h urine urate level was 2.262 mmol/24 h, and her fractional excretion of uric acid (FE-UA) was 2.48 %. Her liver enzymes were normal. The estrogen level and basal body temperature curve were normal for her age and menstrual status. Renal ultrasonography revealed normal kidney size with possible calcium deposits in the bilateral renal medulla. Computed tomography (CT) imaging of her abdomen showed hepatomegaly without nodules. The pelvic ultrasonography and salpingography findings were normal. Serum examinations of her parents and her husband were normal.
Whole blood DNA was extracted from all four family members (the patient, both parents, and her husband) after signing an informed consent form. A genetic study was first conducted with a target gene sequencing approach. A search of the OMIM, NIH, and PubMed databases using the key words “FEMALE,” “GOUT,” and “HYPERLACTACIDEMIA” indicated familial juvenile hyperuricaemic nephropathy, glycogen storage disease type I, and glycogen storage disease type II. Next-generation sequencing was used to sequence each of the exons of the UMOD, RENIN, G6PC, SLC37A4, and GAA genes, as well as two SNP loci (rs2231142 and rs72552713) of ABCG2 found in our previous report of a family including a female with gout.
The genetic sequencing results showed that UMOD, RENIN, SLC37A4, GAA and rs72552713 of ABCG2 were all normal in the patient and her family. Sequencing of the G6PC gene revealed composite heterozygous c.190G>T/c.508C>T mutations in the patient, a heterozygous c.190G>T mutation in her father, and a heterozygous c.508C>T mutation in her mother. The genetic analysis of her husband was normal. The c.190G>T mutation was located on exon 1 and encoded a missense mutation of p.V64L, whereas the c.508C>T mutation was located on exon 4 and encoded a nonsense mutation of p.R170X (Fig. ). Sequencing of 50 healthy females and 100 healthy males at the two loci produced normal results. To our knowledge, the c.190G>T mutation has not been reported in previous literature.
The formula for computing Cockcroft-Gault is given by CrCl = ((140 - age) * adjusted weight * (gender_coefficient)) / (serum creatinine * 72), where the gender_coefficient is 1 if male, and 0.85 if female. The serum creatinine concentration is in mg/dL.
The patient's gender is female, which means that the gender coefficient is 0.85.
The patient is 27 years old. 
The concentration of creatinine is 49.0 µmol/L. We need to convert the concentration to mg/dL. Let's first convert the mass of creatinine from µmol to mg. The mass of creatinine is 49.0 µmol. To convert 49.0 µmol of creatinine to mol, multiply by the conversion factor 1e-06, giving us 49.0 µmol creatinine * 1e-06 mol/µmol = 4.9e-05 mol creatinine. To convert from mol creatinine to grams, multiply by the molar mass 113.12 g/mol, which will give 4.9e-05 mol creatinine * 113.12 g/mol = 0.006 g creatinine. To convert 0.006 g of creatinine to mg, multiply by the conversion factor 1000.0, giving us 0.006 g creatinine * 1000.0 mg/g = 6.0 mg creatinine. The current volume unit is L and the target volume unit is dL. The conversion factor is 10.0 dL for every unit of L. Our next step will be to divide the mass by the volume conversion factor of 10.0 to get the final concentration in terms of mg/dL. This will result to 6.0 mg creatinine/10.0 dL = 0.6 mg creatinine/dL. The concentration value of 49.0 µmol creatinine/L converts to 0.6 mg creatinine/dL. 
The formula for computing the patient's BMI is (weight)/(height * height), where weight is the patient's weight in kg and height is the patient's height in m.
The patient's height is 168.0 cm, which is 168.0 cm * 1 m / 100 cm = 1.68 m. The patient's weight is 55.0 kg. The patient's bmi is therefore 55.0 kg / (1.68 m * 1.68 m) = 19.487 kg/m^2.The patient's BMI is 19.5, indicating they are normal weight.
Because the patient is normal, we take take minimum of the ideal body weight and the patient's body as the patient's adjusted weight for the Cockroft-Gault Equation. Hence, the adjusted body weight is the minimum of the two giving us an adjusted body weight of 55.0 kg.

Using the Cockcroft-Gault equation:
CrCl = ((140 - age) * adjusted weight * gender_coefficient) / (serum creatinine * 72).
Plugging the patient's values gives us ((140 - 27) * 55.0 * 0.85) / (0.6 * 72) = 122.286 mL/min. Hence, the patient's creatinine clearance is 122.286 mL/min.