Obstructive shock is one of the most testable—and most misunderstood—shock states on boards and in clinical medicine. In this episode of One Stem at a Time, we break it down from first principles so you can stop memorizing arrows and start understanding them.

Through two classic board-style cases—cardiac tamponade and pulmonary embolism—you’ll learn how to recognize obstructive shock, interpret hemodynamic profiles, and confidently work through “arrow questions” involving cardiac index, right atrial pressure, pulmonary capillary wedge pressure, and systemic vascular resistance.

We focus on building a simple, powerful framework: follow the flow of blood, identify where it’s blocked, and let the physiology guide you. Along the way, we highlight key distinctions between tamponade, tension pneumothorax, and massive PE, explain why SVR is increased (even in hypotensive patients), and review how PCWP is measured and applied clinically.

By the end of this episode, you’ll be able to:

• Recognize obstructive shock from clinical presentations and exam clues

• Understand the underlying pathophysiology and compensatory mechanisms

• Interpret hemodynamic “arrow” questions with confidence

• Differentiate tamponade, pulmonary embolism, and tension pneumothorax

• Apply high-yield board strategies and clinical reasoning in real time

Perfect for USMLE and COMLEX prep, clinical rotations, and rapid review before exams.

Not all platelet disorders are created equal. We go over the different conditions that involve abnormalities in primary hemostasis for the first part of this miniseries.

Here, through practice question stems, we do a rapid-review of what primary hemostasis is, and quickly go over five different potential causes for platelet deficiency or dysfunction in less than 22 minutes.

In this episode, we go over:

• The physiology and pathology of primary hemostasis, platelets, and its relevant diseases
• Comparing and contrasting different primary hemostasis disorders in patient presentation and lab findings
• The key treatments for conditions such as ITP, TTP, HUS, and more
• Key high-yield USMLE exam traps that often trap students

In this episode, we break down carcinoid syndrome from the ground up, starting with its underlying pathophysiology—how neuroendocrine tumors produce excess serotonin and other vasoactive substances that drive the disease.

We then walk through the key symptoms, including flushing, diarrhea, and bronchospasm, connecting each one back to what’s happening at a biochemical level. From there, we explore complications, including pellagra, and explain how tryptophan depletion leads to this often-overlooked condition.

Next, we shift into management, focusing on the role of octreotide and how it helps control symptoms and prevent progression. We also cover carcinoid crisis, a life-threatening escalation of the disease, discussing common triggers and the importance of rapid recognition and treatment.

Finally, we wrap up with long-term complications, including carcinoid heart disease and its classic association with tricuspid regurgitation, tying everything back to the systemic effects of prolonged serotonin exposure.

This episode offers a cohesive, clinically relevant look at carcinoid syndrome—from mechanism to management to complications.

In this episode, we break down carcinoid syndrome from the ground up, starting with its underlying pathophysiology—how neuroendocrine tumors produce excess serotonin and other vasoactive substances that drive the disease.

We then walk through the key symptoms, including flushing, diarrhea, and bronchospasm, connecting each one back to what’s happening at a biochemical level. From there, we explore complications, including pellagra, and explain how tryptophan depletion leads to this often-overlooked condition.

Next, we shift into management, focusing on the role of octreotide and how it helps control symptoms and prevent progression. We also cover carcinoid crisis, a life-threatening escalation of the disease, discussing common triggers and the importance of rapid recognition and treatment.

Finally, we wrap up with long-term complications, including carcinoid heart disease and its classic association with tricuspid regurgitation, tying everything back to the systemic effects of prolonged serotonin exposure.

This episode offers a cohesive, clinically relevant look at carcinoid syndrome—from mechanism to management to complications.

Struggling to tell DI vs SIADH apart on test day? This episode breaks it down step-by-step—starting with a classic USMLE-style question and ending with the high-yield patterns you need to answer fast and confidently.

We kick things off with a patient presenting with polyuria, polydipsia, hypernatremia, and dilute urine after starting a mood stabilizer—can you identify the diagnosis and next best step? From there, we walk through the full framework for approaching water balance disorders.

In this episode, you’ll learn:
• How to interpret serum vs urine osmolality like a pro
• The key differences between central vs nephrogenic diabetes insipidus
• Why desmopressin response is the ultimate diagnostic clue
• The mechanism behind lithium-induced nephrogenic DI (and why amiloride is the answer)
• A clear, test-day comparison of DI vs SIADH
• High-yield treatment strategies you’ll see on Step 2

Jaundice questions don't have to be confusing. In this rapid review, we break down bilirubin metabolism and classic disorders you'll see on exams: Gilbert, Cringler-Najjar, Dubin-Johnson, and Rotor Syndrome.

Learn how to quickly distinguish between unconjugated vs conjugated hyperbilirubinemia and lock in the diagnosis in seconds.

One stem. One diagnosis. No guesswork.

Not all red eyes are created equal. On exam day, missing the diagnosis can cost you easy points. In this rapid-fire episode of One Stem at a Time, we break down the most high-yield causes of red eye through classical vignettes you'll actually see on STEP and COMLEX.

From the highly contagious "pink eye" to the vision-threatening emergencies like acute angle-closure glaucoma, we'll help you distinguish what's benign from what needs urgent action.

You'll learn how to:

* Differentiate viral, bacterial, and allergic conjunctivitis

* Recognize red flag symptoms like pain, photophobia, vision loss

* Identify must-know diagnoses of keratitis, uveitis, and glaucoma

* Build a fast, reliable approach to any red eye question

Perfect for busy students who want high-yield review without fluff.

In this high-yield episode of One Stem at a Time, we break down hyperkalemia the way board exams (and real patients) demand you understand it.

We walk step-by-step through the physiology of potassium, the classic EKG progression from peaked T waves to sine wave arrest, and the exact treatment algorithm you need to know for exams and the wards. Then we tackle one of the most commonly tested (and most dangerous) clinical pitfalls: potassium management in diabetic ketoacidosis (DKA).

By the end of this episode, you’ll be able to recognize hyperkalemia instantly, treat it in the correct order under pressure, and avoid the classic DKA potassium mistake that trips up students and residents alike.

Perfect for: medical students, COMLEX/USMLE prep, and early residents. Topics covered include hyperkalemia physiology, EKG changes, emergent treatment, insulin effects on potassium, and DKA potassium correction

Press play and master potassium - one stem at a time.

Every clinician has encountered a case that doesn’t quite fit—where the usual explanations fall short and the clues refuse to line up. In this Zebra of the Month episode, we invite you into a diagnostic puzzle that challenges assumptions and rewards careful, deliberate thinking.

With no spoilers and no shortcuts, we unravel the case step by step, highlighting the moments of uncertainty, the subtle details that matter, and the reasoning that keeps rare diagnoses from slipping through the cracks. This episode is about staying curious when the answer isn’t obvious and trusting the process when the path forward feels unclear.

If you enjoy clinical suspense, unexpected turns, and the art of diagnostic reasoning, this is an episode you won’t want to miss!

Hyponatremia is one of the most tested — and most misunderstood — electrolyte disorders. This episode breaks it down into a clear algorithm using volume status, osmolality, and urine studies so you can solve hyponatremia questions with confidence on exams and on the wards.

You’ll learn how to:

• Distinguish real vs “fake” hyponatremia in under a minute
• Use volume status and urine studies to pinpoint the cause
• Recognize classic vignettes like SIADH, cerebral salt wasting, and adrenal insufficiency
• Avoid the most dangerous board trap: osmotic demyelination syndrome

Helpful links for more info:

https://www.ninjanerd.org/podcast/hyponatremia/

https://emcrit.org/pulmcrit/hyponatremia-2/