added eGFR calc and test

README.md

@@ -10,4 +10,4 @@ ArithMedic offers:
 Health‑tech startups, EHR/EMR vendors, AI‑agent‑as‑a‑service platforms, and large healthcare systems that pay for a managed, SLA‑backed medical‑score API.
 
 ### Free / self‑hosted users:
-Clinicians, small med‑tech teams, research labs, universities, and internal dev teams who self‑host WiseMed for privacy, control, or prototyping without per‑use fees..
+Clinicians, small med‑tech teams, research labs, universities, and internal dev teams who self‑host ArithMedic for privacy, control, or prototyping without per‑use fees.

calculators/egfr.py

@@ -0,0 +1,15 @@
+def ckd_epi_2021(serum_creatinine: int, age: int, sex: str) -> int:
+    """Returns estimated GFR in mL/min/1.73 m^2."""
+    if sex == "female":
+        alpha = -0.241
+        k = 0.7
+    else:
+        alpha = -0.302
+        k = 0.9
+
+    result = 142 * min(serum_creatinine/k, 1)**alpha * max(serum_creatinine/k, 1)**(-1.200) * 0.9938**age
+
+    return round(result * 1.012) if sex == "female" else round(result)
+
+print("Female:", ckd_epi_2021(1, 60, "female"))
+print("Male:", ckd_epi_2021(1, 60, "male"))

tests/test_egfr.py

@@ -0,0 +1,25 @@
+import sys
+import os
+
+# Get the directory that contains the 'calculators' folder (the project root)
+project_root = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+# Add the project root to the Python path
+sys.path.append(project_root)
+
+# Now you can import from the calculators module
+from calculators.egfr import ckd_epi_2021 
+
+
+def test_egfr():
+    serum_creatinine = 1
+    age = 60
+    sex = "male"
+
+    assert ckd_epi_2021(serum_creatinine, age, sex) == 86
+
+    serum_creatinine = 1
+    age = 60
+    sex = "female"
+
+    assert ckd_epi_2021(serum_creatinine, age, sex) == 64
+