Your Labs in Real Life — How a PA Actually Thinks Through Your Results

YOUR HEALTH — Issue No. 9

The questions. The reasoning. The decisions. From the exam room to plain language.

Over the past two weeks we covered what your lab results mean — CBC, CMP, iron, B12, lipid panel, thyroid, A1c, PSA, and Vitamin D.

This week we put it all together.

Six patient scenarios. The presenting complaint. The clinical reasoning. The lab orders. The results. And what happened next.

This is how a PA actually thinks through your labs — from the first symptom to the clinical decision.

One thing before we start:

Every patient is different. These scenarios are representative — not prescriptive. What your provider orders and recommends depends on your specific history, medications, symptoms, and clinical context. Use these scenarios to understand the reasoning — not to self-diagnose or self-treat.

Scenario 1 — The Patient Who Was Just “Tired”

70-year-old female. Comes in complaining of fatigue. Sleeping well. No new stress. Has noticed some shortness of breath with exertion. No swelling. No GI symptoms.

The clinical thinking:

Fatigue is one of the most common complaints in primary care — and one of the most nonspecific. The shortness of breath with exertion is the detail that sharpens the picture. That combination — fatigue plus exertional dyspnea (shortness of breath) — raises the question of anemia immediately.

Labs ordered: CBC, CMP, TSH, iron panel

Why TSH? Because hypothyroidism causes fatigue and can look identical to anemia clinically. We want to rule it out at the same time rather than chase one diagnosis and miss another.

Results: Hemoglobin came back at 9.5 g/dL — significantly below normal for a woman her age. MCV was low at 74 fL — microcytic. Ferritin was 6 ng/mL — critically low. TSH was normal. Iron panel confirmed iron deficiency.

The next question — where is the iron going?

Iron deficiency in a 70-year-old woman who is no longer menstruating raises an immediate concern — blood loss. In a postmenopausal woman with new iron- deficiency anemia and no obvious source — a lower GI source needs to be ruled out.

"Have you noticed any changes in your bowel habits? Any blood in the stool?"

She denies any symptoms — but slow, lower GI bleeding can be subtle and easily missed.

The plan: Started oral ferrous sulfate 325mg three times daily. Iron is best absorbed on an empty stomach — but if that causes nausea, taking it with a small amount of food is acceptable. Educated her that her stools would turn dark on iron supplementation — that is expected and not a sign of bleeding. Also counseled on constipation — a common side effect — and recommended increased water and fiber intake.

Referred for colonoscopy. At age 70 with new iron-deficiency anemia — a lower GI source needs to be ruled out regardless of symptoms.

This is the clinical point worth remembering: iron-deficiency anemia in an older adult is not just a nutritional problem until proven otherwise. Find the source.

Scenario 2 — The Patient Who Hadn't Been Seen in Years

57-year-old male. Comes in complaining of increased urination. Takes no medications. No check-up in several years. Has gained approximately 50 pounds over the past year and a half.

The clinical thinking:

Increased urination — polyuria — combined with significant unexplained weight gain in a middle-aged male who hasn't been seen in years tells a clear story before a single lab is ordered. This is new onset diabetes until proven otherwise.

Polyuria is one of the earliest and most common symptoms of uncontrolled diabetes. The kidneys begin spilling glucose into the urine when blood sugar exceeds a certain threshold — pulling water with it and causing frequent urination.

Labs ordered: CBC, CMP, A1c, fasting glucose, PSA

Why hold off on lipids at this visit? Because he has no other diagnoses yet and we need to establish a baseline and confirm the diabetes diagnosis first. Lipids, urine microalbumin, and additional workup will follow at his three month return visit once we have a clearer picture.

Why PSA? He is 57, hasn't been seen in years, and we want to establish a baseline.

Results: A1c came back at 8.0% — confirming Type 2 Diabetes. CMP showed a glucose of 232 mg/dL. Kidney function was normal — GFR above 90. PSA was within normal range.

The plan:

A new diabetes diagnosis carries real emotional weight. Being told you have a chronic condition — and potentially being prescribed an injection on the same day — can feel overwhelming. That conversation matters as much as the prescription.

A GLP-1 medication — such as Ozempic or Mounjaro — was discussed given his A1c of 8.0% and significant weight gain. GLP-1 medications address both blood sugar and weight, simultaneously, making them particularly well suited for a patient like this. However, if he is apprehensive about starting an injectable medication right away — metformin is a reasonable first step. Starting where the patient is comfortable leads to better long term compliance. The GLP-1 conversation can happen at the three month follow-up once trust is established and he has had time to process the diagnosis.

One question worth addressing directly: Can't he just control this with diet alone?

Absolutely — and some patients do. But, with an A1c of 8.0% and a glucose of 232, I would rather put the brakes on early and stabilize the disease sooner than later. Uncontrolled glucose causes damage quietly — to kidneys, eyes, and nerves — often before symptoms appear. Starting medication now does not mean staying on it forever. If he commits to dietary changes and loses weight, I am always open to stepping down or stopping medication when the numbers support it. The goal is control — not a lifetime prescription.

Counseled extensively on low carbohydrate and low sugar dietary changes. Compliance with diet changes at this stage can be as impactful as medication — especially in a newly diagnosed patient.

Home glucose monitoring was discussed but intentionally not pushed at this first visit. The goal was not to overwhelm him with devices and data on day one. Get the medication started, the diet changes underway, and revisit monitoring at the three month follow-up when he has had time to adjust.

"I want to see you back in three months. At that visit we will check your A1c again, add lipids, check your urine for early signs of kidney stress, and talk about any additional medications that may help protect your kidneys and heart."

Scenario 3 — The Routine Three Month Visit

65-year-old female with Type 2 Diabetes, hypertension, and Stage 3a chronic kidney disease. Here for her regular follow-up. Feeling well. No new complaints.

The clinical thinking:

A well-controlled diabetic patient at a routine visit has a predictable lab order — but each value tells a specific story and each result drives a specific clinical decision.

Labs ordered: A1c, CMP, CBC, lipid panel, TSH, urinalysis, urine microalbumin/creatinine ratio, Vitamin D

Vitamin D is checked once or twice annually in this patient using her CKD diagnosis as the qualifying indication — a practical example of how a diagnosis on your chart determines what labs your insurance will cover. Without the CKD diagnosis on the order, Vitamin D testing would not be covered and she would receive a bill for it.

The urine microalbumin/creatinine ratio is checked at least annually in every diabetic patient. It detects protein leaking into the urine — an early marker of diabetic kidney damage — before it shows up on a standard CMP.

What we are looking for at this visit:

A1c — is she at goal? For a 65-year-old with diabetes and hypertension, the target is below 7.0%. If her A1c has risen since last visit — why? Dietary changes? Medication adherence? A new stressor?

LDL — diabetic patients have an LDL goal below 70 mg/dL. This is lower than the general population goal because diabetes itself is a cardiovascular risk factor. If her LDL is above 70 — is she on a statin? Is the dose adequate?

CMP — kidney function trending stable? Any electrolyte changes? Her blood pressure medications affect potassium — worth checking.

CBC — any new anemia? Any changes in white count?

TSH — thyroid dysfunction is more common in diabetic patients and in women. An annual TSH catches changes before they affect glucose control or energy levels.

Results — no concerning changes from prior visit:

A1c stable at 6.8% — at goal. LDL at 64 mg/dL — below the 70 target. GFR stable. Urine microalbumin normal. TSH normal. Vitamin D mildly insufficient — supplement recommended.

The plan:

Continue current medications. Start Vitamin D3 supplementation. Reinforce dietary compliance. Return in three months.

This is what a well-managed chronic disease visit looks like. No drama. Steady monitoring. Small adjustments when needed. The goal is catching changes early — not waiting for symptoms.

Scenario 4 — The New Patient Whose Medication Was the Problem

70-year-old female. New to the practice. Comes in to establish care. Has hypertension — well-controlled on triamterene/hydrochlorothiazide. Denies any history of kidney disease.

The clinical thinking:

A new patient visit means establishing a complete baseline. We don't know her prior lab history — so everything we order today becomes her reference point going forward.

Labs ordered: CMP, CBC, A1c, lipid panel, TSH, urinalysis

Results: GFR came back at 45 — Stage 3a chronic kidney disease range. BUN was also elevated. Blood pressure well controlled. Glucose normal.

The immediate questions:

Has she ever had a GFR checked before? We don't know — she's new. Is this chronic or acute? The elevated BUN alongside the low GFR suggests dehydration may be contributing.

Is she taking any NSAIDs (ex. ibuprofen, naproxen)? She denies.

The clinical picture points toward her medication. Triamterene/hydrochlorothiazide is a combination tablet containing two diuretics in one — both working to reduce fluid volume. In older patients who may not be drinking adequate fluids, the kidneys can bear the consequences of that reduced volume.

The plan:

Changed her blood pressure medication — discontinued the triamterene/hydrochlorothiazide and started an ARB — medications in this class include losartan, valsartan, and olmesartan — which is well tolerated in patients with reduced kidney function and provides additional renal protection.

Counseled on hydration — particularly important now that she is no longer on a diuretic.

Rechecked labs in one month.

One month follow up:

GFR returned to 70 — Stage 2. BUN normalized. Blood pressure remained well controlled on the new medication.

This is the clinical point: a single low GFR in a new patient does not immediately mean chronic kidney disease. Context matters. Her GFR improved significantly with a medication change and hydration — suggesting the diuretic was the primary driver, not progressive kidney damage. She still has mildly reduced kidney function worth monitoring — but the trajectory is now reassuring rather than concerning.

Scenario 5 — The PSA That Changed Over Time

50-year-old male. Comes in for annual wellness visit. No symptoms. Feels well.

The clinical thinking:

Annual wellness visit for a 50-year-old male includes PSA as part of a prostate health discussion. He has been coming in every year — and his PSA has been tracked.

PSA trend:

Each individual value is within or at the upper range of normal. Taken in isolation — no single reading would trigger urgent concern. But the trend tells a different story.

His PSA rose 0.8 ng/mL in year one and 1.0 ng/mL in year two — a consistent and accelerating upward trend that warrants further evaluation, regardless of the absolute value.

Added at this visit: Free PSA

Why free PSA? His total PSA is now at 4.0 — the threshold where the ratio of free to total PSA becomes clinically meaningful. A lower percentage of free PSA increases concern for prostate cancer. A higher percentage suggests a benign cause like BPH. This one additional test helps guide whether to proceed to Urology referral or monitor further.

The plan:

Repeat PSA in 4-6 weeks to confirm the value is not a transient elevation. Add free PSA. Refer to Urology for evaluation given the consistent upward trend.

This scenario illustrates exactly why annual PSA monitoring matters — not to catch a single abnormal value, but to detect meaningful change over time. Without three years of annual readings, this patient's PSA velocity would be invisible. With them — we know exactly when something changed and can act accordingly.

Scenario 6 — The Patient Who Blamed Everything on Getting Older

50-year-old female. Comes in complaining of weight gain, fatigue, and constipation over the past several months. Attributes it to getting older and stress.

The clinical thinking:

Weight gain, fatigue, and constipation is a triad that immediately raises thyroid on the differential. These three symptoms together — particularly in a middle-aged woman — are classic hypothyroidism until proven otherwise.

Labs ordered first visit: TSH, CMP, CBC

TSH is the primary target given her symptom triad. CMP gives us a broad metabolic picture — looking for electrolyte abnormalities, elevated glucose suggesting diabetes, and kidney function baseline. CBC screens for anemia as a contributing cause of fatigue. We order what is clinically justified and covered — not everything at once.

Results: TSH came back elevated at 8.2 mIU/L — significantly above normal. CMP and CBC were within normal limits.

Now that we have a diagnosis — hypothyroidism confirmed — we add: Free T4 and TPO antibodies — now covered by the hypothyroidism diagnosis. Free T4 confirms the degree of dysfunction. TPO antibodies identify the underlying cause.

Additional results: Free T4 was low, confirming hypothyroidism. TPO antibodies were positive — confirming Hashimoto's thyroiditis as the underlying cause.

Vitamin D: The patient has a history of low Vitamin D and is currently taking OTC Vitamin D3 1,000 IU daily. Because she is already on supplementation, I would expect her level to be stable — but it is worth checking using a Vitamin D deficiency diagnosis to ensure she is in an adequate range and that her current supplement dose is not contributing to her ongoing fatigue.

The diagnosis: Hypothyroidism secondary to Hashimoto's thyroiditis.

The plan:

Started levothyroxine — the synthetic thyroid hormone used to replace what the thyroid is no longer producing adequately. Dosing is weight-based and individualized — typically started low and titrated up based on TSH response.

Educated the patient that levothyroxine is taken on an empty stomach — ideally 30-60 minutes before eating — and that certain supplements including calcium and iron can interfere with absorption if taken at the same time.

Recheck TSH in 6-8 weeks after starting levothyroxine to assess response and adjust dose, if needed. Once stable on the correct dose, TSH monitoring moves to every 6-12 months.

Importantly — her symptoms will not resolve overnight. Thyroid hormone replacement takes weeks to months to fully take effect. Setting that expectation upfront prevents frustration and unnecessary dose adjustments too early.

"The good news is we found the answer. The better news is it's very treatable. The honest news is it takes a little time to feel the full benefit — but you should start noticing improvement within a few weeks."

A full Plain Medicine issue on thyroid — Hashimoto's, hyperthyroidism, treatment, and the questions worth asking your provider — is coming soon.

One final note on labs — something worth saying plainly:

Regular lab work is one of the most powerful tools in medicine — not because it catches dramatic problems, but because it catches quiet ones. The 70-year-old who felt tired. The 57-year-old who hadn't been seen in years. The 50-year-old whose PSA crept up one point at a time.

None of them felt seriously ill. All of them had something worth finding.

If you have diabetes or chronic kidney disease — get labs every 3-4 months. If you take medications that affect your kidneys, electrolytes, or blood count — get labs at least twice a year. If you are generally healthy with no chronic conditions — once a year is reasonable.

The hardest thing to treat is something you didn't know was there.

The Member deep-dive this week goes deeper on each scenario — the full clinical reasoning behind every lab ordered, what would have changed the plan if results came back differently, and the specific medication decisions and patient education points that don't make it into a standard appointment.

Next week: The Medicare GLP-1 Bridge — starting July 1, Medicare patients can access Wegovy (oral and injectable), Zepbound, and Foundayo for $50/month. Everything you need to know before it launches.

Plain Medicine is published for educational purposes only and does not constitute medical advice or establish a patient-provider relationship. Always consult your healthcare provider before making medical decisions.

— Kyle